US4.489.640 discloses a vehicle door operating apparatus. The apparatus is arranged to close and open a door of a transit bus through a spindle drive and a rod arrangement. The door operating apparatus comprises a rack and pinion assembly. The rack is formed as an extension of a piston which slides within a power cylinder formed by an apparatus housing. Movement of the piston and rack in a linear direction causes a pinion gear to convert a linear motion to rotate a spindle shaft to which an operating rod and spindle mechanism of the door is slidably keyed. Pressurising air is admitted to the operating power cylinder to cause door movements and to keep the door in a lifted locked position.

Further, a feature is provided which permits a manual opening of the vehicle door in an absence of pressurised air during an emergency situation. Without pressurised air, the vehicle door lowers to an unlocked position in which the vehicle door can be manually operated.

A pneumatic operation of a bus door is common in the market. The possibility of a manual pressure relief is considered as a reliable solution to allow a manual operation of a bus door during an emergency situation. During the manual operation, the passenger may grab the bus door by his hand to push the bus door to an open position. Often an emergency handle or button is provided to release the bus door, such that a passenger himself can cause the pressure relief of the pneumatic system which subsequently allows said manual operation of the bus door.

However, the pneumatic operation of the bus door has a drawback in that the passenger bus needs to be equipped with an air supply system. The air supply system serves primary for operating the bus doors in the normal operational state, but also to re-establish the vehicle door operating apparatus after a pneumatic release during an emergency situation. The air supply system is equipped with an air compressor to pressurise the apparatus again to return to the normal operational state. Disadvantageously, the air supply system introduces a lot of components and increases a technical complexity of the bus door operating system considered as a whole.

The general object of the present invention is to at least partially eliminate the above mentioned drawback and/or to provide a usable alternative. More specific, it is an object of the invention to provide a vehicle door operating system which is operatable without dependency of an air supply equipment of a passenger bus. More in particular, it is an object of the invention to provide a vehicle door operating system which can be re-established to an operational state without an air compressor.

According to the invention, this object is achieved by a vehicle door operating system according to claim 1.

According to the invention a vehicle door operating system for operating a vehicle door is provided. The vehicle door operating system is in particular a bus door operating system.

The vehicle door operating system comprises a vehicle door operating mechanism which is connectable to the vehicle door. Further, the vehicle door operating mechanism comprises a door actuator which is connectable to set mechanism to move the vehicle door to and fro an open and closed position.

The vehicle door operating system includes a hydraulic actuating circuit for actuating the door actuator. Additionally, the vehicle door operating system comprises an emergency circuit for allowing a manual operation of the vehicle door in case of an emergency. A manual operation means a pressure release of the door actuator whereafter a person is able to open the vehicle door by hand. The person can grab and move the vehicle door by hand.

The actuating circuit comprises a double acting hydraulic cylinder. The hydraulic cylinder forms the door actuator. The cylinder has a housing and a piston. A piston rod is connected to the piston. The piston subdivides the housing in a pull chamber at a side of the piston rod and a push chamber at the other side of the piston.

The actuating circuit comprises a pump unit which is adapted to be operatively connected to the hydraulic cylinder. The pump unit includes a pump which is driveable by a pump motor to actuate the hydraulic cylinder to extend and retract the piston rod. The emergency circuit comprises a bypass conduit. The bypass conduit is fluidly connected in between the first conduit and the second conduit. The first conduit is fluidly connected to the pull chamber of the hydraulic cylinder. The second conduit is fluidly connected to the push chamber of the hydraulic cylinder. The bypass conduit fluidly interconnects the first and second conduit. The emergency circuit comprises an emergency valve. The emergency valve is positioned at the bypass conduit. The emergency valve is arranged to open or close the bypass conduit. In the operational state of the vehicle door operating system, the emergency valve is adapted to be closed. In case of an emergency, the emergency valve is adapted to be opened to interrupt the operational state.

Further, the emergency circuit comprises a single acting pneumatic cylinder. The pneumatic cylinder is operatively connected to the emergency valve. The pneumatic cylinder has a pressure chamber which is fluidly connected by a pneumatic conduit to a pressure relief valve. The pressure relief valve is adapted to be manually operated in case of an

emergency. An opening of the pressure relief valve will depressurise the pressure chamber and cause an opening of the emergency valve.

Further, the emergency circuit comprises a reset cylinder. The reset cylinder serves to reestablish the vehicle door operating system to the operational state. The reset cylinder comprises a housing and a piston. The piston is movable positioned inside the housing. The piston defines a hydraulic reset chamber and a pneumatic pump chamber inside the housing. The piston is positioned in between the reset chamber and the pump chamber. The reset cylinder comprises a pump spring. The pump spring exerts a spring force onto the piston to expand the pump chamber. The pump spring counteracts a force generated by the reset chamber. The pump spring may be positioned inside the pump chamber to press onto the piston. Alternatively, the pump spring may be positioned inside the reset chamber to retract the piston. In a variant, the pump spring may be positioned around a piston shaft in between a first and second piston portion, in which a first pump spring end engages the housing of the reset cylinder and a second pump spring end engages a piston portion.

The pump chamber has a first port which forms an air-inlet. The first port is provided with an inlet check valve which allows an inlet of air into the pump chamber. The pump chamber has the second port which forms an air-outlet. The second port is provided with a check valve which allows an air flow out of the pump chamber. The second port of the pump chamber is adapted to be fluidly connected with said pressure chamber of said pneumatic cylinder. A fluid connection by a pneumatic conduit between the pump chamber and the pressure chamber enables a pressurising of the pneumatic cylinder. Further, the emergency circuit comprises a reset valve. The reset valve is adapted to be closed during an operational state of the vehicle door operating system and adapted to be opened in case of an emergency. The reset valve is adapted to fluidly connect the reset chamber of the reset cylinder with the pump unit to start a re-establishment of the vehicle door operating system. A third hydraulic conduit extends in between the reset valve and the reset chamber for hydraulically pressurising the reset chamber.

The vehicle door operating system according to the invention may provide several advantages.

A major advantage is that a vehicle door is operated by a hydraulic door actuator, while at the same time a commonly accepted air-pressure release is still available in case of an emergency situation. For normal operation, the hydraulic actuation of the vehicle door no longer requires a connection to an air supply system of a vehicle. Additionally, also a re-establishment of the vehicle door operating system after an emergency situation does not require a connection to the air supply system. An electrically driven compressor is not necessary to reset the vehicle door operating system to the normal operational state. By operating the reset cylinder, the pneumatic cylinder is pressurised and the emergency valve is closed.

A hydraulic operation of a vehicle door may provide further benefits in the operational state.

In comparison with a pneumatic operation, the hydraulic operation of the vehicle door can be carried out more silently which contributes to a passengers comfort.

Due to a compressibility of air, a pneumatic operated vehicle door may flap or vibrate in its position. A hydraulic operated vehicle door may be more stably positioned. Due to a hydraulic resistance of a fluid flow in between the pull and push chamber of the door actuator, a vehicle door can be stably maintained in position during the normal operational state.

In an embodiment of the vehicle door operating system according to the invention, the piston of the reset cylinder has a first piston surface, a first end face, which is directed to the reset chamber which is smaller than a second piston surface, a second end face, which is directed to the pump chamber. The reset cylinder is a hydraulic-pneumatic cylinder. The pump chamber has a volume which is determined by an air volume and/or operational air pressure which is necessary for pressurising the pneumatic cylinder to act the emergency valve. The piston of the reset cylinder is movable about a certain piston stroke necessary to compress and pressurise the air volume. A pump capacity necessary to move the piston by supplying a hydraulic fluid to the reset chamber may be reduced by reducing a diameter of the first end face. In particular, the first end face is at least a factor two, more in particular a factor four, smaller than the second end face.

In an embodiment of the vehicle door operating system according to the invention, the piston comprises a piston shaft. The piston shaft has a first and second shaft end. The piston shaft is positioned in between a first and second piston portion. The first and second piston portion are respectively connected to the first and second shaft end. The first and second piston portion respectively form a first and second piston end face. The first piston end face delimits the reset chamber. The second piston end face delimits the pump chamber.

In an embodiment of the vehicle door operating system according to the invention, the reset cylinder is a double piston cylinder. The reset cylinder comprises two pistons. The two pistons are positioned inside a reset cylinder housing. The two pistons are separate and movable with respect to each other. A first piston delimits the reset chamber. The first piston is a hydraulic piston. The reset chamber is positioned in between a proximal housing end face and the first piston. A second piston delimits the pump chamber. The second piston is a pneumatic piston. Here, the pump chamber is positioned in between the first and second piston. A single pump spring may be positioned inside the pump chamber, such that the pump spring exerts a pushing spring force to both the hydraulic and pneumatic piston.

Preferably, the single pump spring only engages the hydraulic piston, e.g. by positioning the pump spring around the piston shaft in between the housing and the hydraulic piston, to prevent a death space inside the pump chamber.

In an embodiment of the vehicle door operating system according to the invention, the double piston cylinder is a hydraulic-pneumatic cylinder comprising a hydraulic reset chamber which is adapted to be hydraulically connected to the pump unit to actuate the first piston and a pneumatic pump chamber which is adapted to be pneumatically connected to the pressure chamber by a pneumatic conduit.

In an embodiment of the vehicle door operating system according to the invention, the second piston is connected to a piston rod which extends outside the reset cylinder housing. The piston rod of the reset cylinder is adapted to be operatively connected to the piston rod of the hydraulic cylinder which actuates the vehicle door. Preferably, the piston rods are indirectly connected to each other via the vehicle door operating mechanism, e.g. via a rack and pinion component. Preferably, the second piston of the reset cylinder and the piston rod of the hydraulic cylinder are connected to each other by an abutting engagement from a certain position. The abutting engagement occurs when the piston rod of the hydraulic cylinder (indirectly via another component) hits against the second piston after which the second piston travels together with the piston rod of the hydraulic cylinder. As a

consequence of the interconnection, a movement of the piston rod of the hydraulic cylinder causes a movement of the piston rod of the reset cylinder. In other words, a movement of a vehicle door from an intermediate position to an extreme position operates the reset cylinder. Herewith, the second piston of the reset cylinder is displaceable by the piston rod of the hydraulic cylinder. The second piston is displaceable from an initial position which corresponds with a vehicle door positioned at an intermediate position to an extreme position corresponding with a vehicle door in the open position. Advantageously, the displacement of the second piston of the reset cylinder by a displacement of the piston rod of the hydraulic cylinder causes a pumping action. The displacement of the second piston results in a compression of the pump chamber which subsequently results in a pressurising of the pressure chamber of the pneumatic cylinder to carry out a re-establishment of the vehicle door operating system.

In an embodiment of the vehicle door operating system according to the invention, the pump chamber of the reset cylinder is formed by a plurality of pump sub-chambers. The pump sub- chambers are fluidly interconnected. The pump sub-chambers may be spaced from each other inside the reset cylinder housing. Preferably, the pump sub-chambers are housed in separate sub-housings which advantageously allow a distribution of the sub-housings in a narrow installation space in a neighbourhood of a vehicle door. Optionally, each pump sub- chamber is connected to a common safety relief valve. Advantageously, just a single safety relief valve needs to be connected to prevent an overload of the pump chamber.

In an embodiment of the vehicle door operating system according to the invention, the pump chamber comprises at least a first and a second pump sub-chamber, wherein the first pump sub-chamber is delimited by the first piston of the reset cylinder and a distal housing end face of the reset cylinder housing. In a further embodiment, an interconnected second pump sub-chamber is housed in a separate housing and delimited by the second piston of the reset cylinder. A displacement of the second piston compresses the second pump sub- chamber and also pressurises the interconnected first pump sub-chamber. Preferably, the second piston has a smaller diameter in cross-section than the second end face of the first piston. ln an embodiment of the vehicle door operating system according to the invention, the emergency valve has a valve housing. The valve housing has a first channel which is adapted to fluidly connect the bypass conduit of the emergency circuit. Preferably, the first channel is a through bore from one side of the valve housing to an opposite side.

Preferably, the valve housing has a mounting surface for mounting the pneumatic cylinder. The valve housing comprises an intersecting channel which originates from the mounting surface and intersects the first channel. The emergency valve comprises a closure element which is movable positioned inside the intersecting channel. The closure element is connectable to the pneumatic cylinder. The closure element is movable by the pneumatic cylinder to open or close the first channel. Herewith, the pneumatic cylinder operates the emergency valve.

In an embodiment of the vehicle door operating system according to the invention, the reset valve is adapted to be operatively connected to said pneumatic cylinder. Both the emergency valve and the reset valve are adapted to be opened and closed by the same pneumatic cylinder.

In an embodiment of the vehicle door operating system according to the invention, the reset valve and the emergency valve are incorporated and comprise a common valve housing.

In particular, the valve housing of the emergency valve comprises a second channel which is adapted to fluidly connect a hydraulic conduit of the emergency circuit to interconnect the reset valve with the reset cylinder. Preferably, the second channel is a through bore from one side of the valve housing to an opposite side. Preferably, second channel extends in parallel with the first channel. The intersecting channel intersects both the first and second channel. The closure element is adapted to open or close both the emergency valve and the reset valve. Advantageously, the reset valve and the emergency valve are incorporated in one structural component. In an embodiment of the vehicle door operating system according to the invention, the third conduit which extends from the reset valve to be reset cylinder is branched by a branch conduit to a reservoir of the hydraulic circuit, wherein the branch conduit comprises a throttle. The branch conduit may extend directly from the third conduit to the reservoir or indirectly, e.g. from the third conduit via a check valve and a shuttle valve of the pump unit to the reservoir. The throttle is preferably always open and allows a certain fluid flow rate which serves to reduce a volume of the reset chamber. A fluid flow rate conducted by the third conduit which is larger than this throttled fluid flow rate will cause the reset chamber to expand. After an expansion of the reset chamber has been carried out, the throttle ensures a return of the reset chamber to an initial state. The throttle is preferably simply embodied as an orifice or may alternatively be embodied as a throttle valve.

In an embodiment of the vehicle door operating system, the hydraulic actuating circuit comprises a circuit section in between the push and pull chamber and including the bypass conduit which circuit section comprises a non-return valve. The non-return valve is adapted to prevent a fluid flow in a direction from the push chamber to the pull chamber of the hydraulic cylinder. Preferably, the non-return valve is positioned in the circuit section at a position in between the pull chamber and the emergency valve. In an embodiment of the vehicle door operating system, the manually operatable pressure relief valve comprises a switch. The switch may be formed by a button or handle. The switch is configured to be operated by a hand of a person.

In a further embodiment of the vehicle door operating system, the system further comprises a lock cylinder for locking a vehicle door. The lock cylinder is movable to and fro a lock and unlock position.

Further, the invention relates to an emergency valve assembly. The emergency valve assembly comprises a single acting pneumatic cylinder and a valve housing. The valve housing comprises a first channel for connecting a bypass conduit, a second channel for connecting a conduit to a reset cylinder and an intersecting channel which intersects the first and second channel. The emergency valve assembly further comprises a closure element which is adapted to be moved inside the intersecting channel to open or close the first and second channel. The valve housing has a mounting surface for mounting the pneumatic cylinder and connecting the pneumatic cylinder to the closure element. By actuating the pneumatic cylinder, the closure element is moved to open or close the first and second channel.

In an embodiment of the emergency valve assembly according to the invention, the emergency valve assembly further comprises a non-return valve which is fluidly connected with the first channel. ln an embodiment of the emergency valve assembly according to the invention, the valve housing further comprises a third channel to form a lock emergency valve. The lock emergency valve is adapted to unlock a lock cylinder in case of an emergency. The intersecting channel intersects both the first, second and third channel. By actuating the closure element, the lock emergency valve is actuable together with the emergency valve and a reset valve.

Further, the invention relates to a reset cylinder for re-establishing a vehicle door operating system according to the invention. The reset cylinder comprises a housing and a piston. The piston is positioned inside the housing in between a hydraulic reset chamber and a pneumatic pump chamber. The reset cylinder comprises a pump spring. The pump spring exerts a spring force onto the piston for expanding the pump chamber. The pump chamber has a first port which is provided with an inlet check valve which allows an inlet of air into the pump chamber. Further, the pump chamber comprises a second port which is provided with an outlet check valve which allows an air flow out of the pump chamber. The pump chamber is adapted to be fluidly connected with a pressure chamber of a pneumatic cylinder for pressurising that pressure chamber.

Further, the invention relates to a method for operating a vehicle door, e.g. a swingable bus door, comprising the following steps of providing a vehicle door system according to the invention; operating the vehicle door in an operational state of the vehicle door system; manually switching the vehicle door system to a non-operational state in case of an emergency situation by operating a pressure relief valve to cause a pneumatic pressure relief and to open an emergency valve; closing the pressure relief valve; re-establishing the vehicle door system to return to the operational state by actuating a reset cylinder including a pump chamber to pressurise a pneumatic cylinder to close the emergency valve.

Further preferred embodiments are defined in the subclaims. The invention will be explained in more detail with reference to the appended drawings. The drawings show embodiments according to the invention, which may not be interpreted as limiting the scope of the invention. Specific features may also be considered apart from the shown embodiments and may be taken into account in a broader context as a delimiting feature, not only for the shown embodiment but as a common feature for all embodiments falling within the scope of the appended claims, in which: Fig. 1A, 1 B and 1 C show in a perspective and frontal view an operating system for operating a swing door of a transit bus;

Fig. 2 shows a schematic view of a hydraulic circuit of a vehicle door operating system; Fig. 3 shows in a schematic view a vehicle door operating system according to the invention which comprises the hydraulic circuit as shown in fig. 2 which is further extended by an emergency circuit according to the invention, in which the vehicle door operating system is in an operational state;

Fig. 4 shows in a schematic view the vehicle door operating system in an emergency state in which an emergency valve is opened and a vehicle door is manually operatable;

Fig. 5 shows in a schematic view a re-establishment of the vehicle door operating system, in which the emergency valve is to be closed to return to the operational state; Fig. 6 shows in a schematic view a next step in the re-establishment in which the emergency valve is closed and in which a reset valve is to be closed;

Fig. 7 shows in a schematic view a full stroke state of a door actuator corresponding with a full open vehicle door;

Fig. 8 shows in a schematic view an alternative embodiment of a double piston cylinder which is connected to the emergency circuit;

Fig. 9 shows in a schematic view a vehicle door operating system which further comprises a lock cylinder;

Fig. 10 shows in a schematic view an embodiment of the vehicle door operating system including an alternative configuration of a reset cylinder; and

Fig. 1 1 shows a schematic view of an emergency valve assembly which incorporates both an emergency valve and a reset valve.

In Figs. 1-1 1 , a vehicle door operating system is denoted overall by reference numeral 1. Identical reference signs are used in the drawings to indicate identical or functionally similar components. Fig. 1A shows in a frontal view a vehicle door 18, which is here a bus door of a passenger bus 17, also called a transit bus. A pair of bus doors is illustrated in a closed position. Each bus door 18 is connected by a shaft arm 195 to an upright shaft 193. The shaft 193 is rotatable by a vehicle door operating system 1 to move the bus door 18 from the closed to an open position and vice versa. The vehicle door operating system 1 is positioned above the vehicle door 18 and connected to a chassis 171. Fig. 1 B is an enlarged view of Fig. 1A which shows the vehicle door operating system 1 in further detail. At a bottom region, the upright shaft 193 is rotatable connected to a bus floor of the bus 17. At a top region, the upright shaft 193 is connected to a linear door actuator 10, which is here a pneumatic cylinder, of the vehicle door operating system 1. The door actuator 10 is positioned above the bus door 18. The door actuator 10 is connected to a shaft flange 194 at the top region of the shaft 193. The door 18 is connected by a shaft arm 195 to the shaft 193, such that a rotational movement of the shaft 193 causes the door 18 to move. At an upper and a lower corner, the door 18 is slidably connected by a slider 196 to the chassis 171 , such that an actuation of the door actuator 10 causes the door 18 to swing. The door 18 is swingable in between a closed, see fig. 1A, and open position, see Fig. 1 C, to allow passengers to enter the bus.

In Fig. 1 C the pair of bus doors are illustrated in the open position. Each bus door 18 is rotated over an angle of about 90°. To move the bus door from the closed to the open position, the rotation of the bus doors is directed inwardly into an inner space of the bus.

Fig 2 discloses a hydraulic circuit 100 of a vehicle door operating system 1 which includes a door actuator for operating a vehicle door 18 of a vehicle 17. Here, the door actuator is a double-acting hydraulic cylinder 10. The hydraulic cylinder 10 is a linear cylinder to provide a linear movement. The hydraulic cylinder comprises a housing 1 1 which is subdivided by a piston 12 into a first chamber, also called a pull chamber 121 and a second chamber, also called a push chamber 122. At a side of the pull chamber 121 , the piston 12 is connected to a piston rod 13 which extends in an axial direction. A distal end of the piston rod 13 is connected to a vehicle door operating mechanism 19, which is here rack and pinion mechanism. The piston rod 13 is connected to a rack 191 of the rack and pinion mechanism. The rack 191 is connected to a pinion 192. The piston rod 13 is outwardly and inwardly movable to respectively open and close a vehicle door 18. The rack and pinion mechanism converts a linear movement provided by the door actuator 1 to a rotating movement. The rack and pinion mechanism is connectable to a rotatable member of a vehicle door assembly to operate a movement of a vehicle door 18. The vehicle door is in particular a swing door of a transit bus.

The door actuator is actuable by a control unit (not shown). The control unit is electronically connected to a hydraulic actuating circuit 100 for hydraulically operating the door actuator.

The door actuator is operatively connected to a pump unit 20. The pump unit 20 comprises a bi-directional pump 21 and a pump motor 22. The bi-directional pump 21 is driveable in two directions (clockwise and counter-clockwise) to operate the double-acting hydraulic cylinder 10. A first pump port 21.1 of the pump 21 is hydraulically connected by a hydraulic conduit 101 to the pull chamber 121. A second pump port 21.2 of the pump 21 is hydraulically connected by a hydraulic conduit 102 to the push chamber 122. A pilot operated check valve 21.3, 21.4, here a pressure operated check valve POCV1 , POCV2, is provided in between each pump port 21.1 , 21.2 and the hydraulic cylinder.

Further, the pump unit 20 comprises a shuttle valve 23 and a reservoir 24. The hydraulic actuating circuit 100 comprises at least one pressure safety valve RV1 , RV2 to prevent an overload of the hydraulic circuit 100. Such a configuration of a pump unit 20 is generally known.

Fig. 3 shows the actuating circuit 100 as shown in Fig. 2 which circuit is extended with an emergency circuit 200. The piston rod 13 of the hydraulic cylinder 10 is shown in a retracted position which corresponds with a connected vehicle door in a closed position. The circuit as shown in Fig. 3 represents a operational state of the vehicle door operating system. In the operational state, a door of the vehicle door operating system can be operated from the open to the closed position and vice versa. In Fig. 3, the hydraulic cylinder 10 is stably kept in position by a hydraulic pressure in the pull and push chambers 121 , 122. The emergency circuit 200 serves to allow a manual opening of the vehicle door in case of an emergency. A vehicle door which is initially in the closed position can be opened by a passenger or by someone from outside the vehicle when releasing a hydraulic resistance in between the chambers 121 , 122 of the hydraulic cylinder 10.

To release the hydraulic resistance, a bypass conduit 201 is provided. The bypass conduit 201 extends in between the pull and push chamber 121 , 122 of the hydraulic cylinder 10. The bypass conduit 201 is here connected to the hydraulic conduit 101 which extends to the pull chamber 121 and the hydraulic conduit 102 which extends to the push chamber 122 of the hydraulic cylinder 10. The bypass conduit 201 comprises a valve 210 which is closed during the operational state of the vehicle door operating system 1.

Further, the circuit section in between the pull and push chamber and including the bypass conduit 201 comprises a non-return valve 211 which prevents a fluid flow from the push chamber 122 to the pull chamber 121 of the hydraulic cylinder 10. Here, the non-return valve 21 1 is positioned in between the emergency valve 210 and the closed chamber 122, but the non-return valve 21 1 can also be positioned at the other side of the emergency valve 210 in between the emergency valve 210 and the pull chamber 121. ln case of an emergency, the emergency valve 210 can be opened. Here, the emergency valve 210 is adapted to be operated by a single-acted pneumatic cylinder 220. In the operational state of the vehicle door operating system, the pneumatic cylinder is

pressurised. When pressurised, the pneumatic cylinder 220 maintains the emergency valve 210 in a closed position. The bypass-conduit 201 remains closed. When the pneumatic cylinder 220 is de-pressurised, the emergency valve 210 is operated and moved from a closed to an open position.

The pneumatic cylinder 220 can be de-pressurised by manually opening a relief valve 227. The relief valve 227 is fluidly connected with a pressure chamber 221 of the pneumatic cylinder 220 to de-pressurise the pneumatic cylinder in case of emergency. The relief valve 227 may be located in a separate pneumatic conduit 202 or may be directly mounted to the pneumatic cylinder 220. The pressure chamber 221 is positioned at one side of a piston 222 of the pneumatic cylinder 220. A spring 223 acts on the opposite side of the piston 222 to counteract the pressure chamber 221. The spring 223 exerts a spring force to de-pressurise the pressure chamber 221 and retract the piston 222.

Here, the relief valve 227 is a manually operated relief valve which has a switch. The switch is adapted to be manually operated e.g. by pressing a button or handling a bar by a person.

Fig. 4 shows the vehicle door operating system 1 having a door in an intermediate position as possible in an emergency situation. Due to a hydraulic flow resistance in between the pull and push chamber 121 , 122, the intermediate position is stable. The relief valve 227 is open, such that the pressure chamber 221 of the pneumatic cylinder 220 is de-pressurised. As a result, the emergency valve 210 is opened which has opened the bypass conduit 201. The arrows at respectively the first conduit 101 , the bypass conduit 201 , the second conduit 102 indicate the circuit section for a fluid flow from the pull chamber 121 to the push chamber 122 of the hydraulic cylinder 10 which corresponds with a movement of opening a vehicle door. The door is movable to the full open position. The movement of the door can be carried out by an external force delivered by a person. When opening the vehicle door, the piston rod 13 of the hydraulic cylinder 10 is extending from the housing 1 1 (as indicated by the arrow above the rack 191. The piston rod of the door actuator 10 is outwardly moving.

The combination of the emergency valve 210 and non-return valve 211 allows a one- direction fluid flow through the bypass-conduit 201 from the pull chamber 121 to the push chamber 122 of the hydraulic cylinder 10. When the bypass-conduit 201 is open, an extension of the piston rod 13 is not obstructed to allow a person to open the vehicle door which is connected to the door actuator 1.

As further shown in Fig. 4, the emergency circuit 200 comprises a reset cylinder 230 configured as a double piston cylinder 230. The double piston cylinder 230 is positioned opposite the door actuator 10. The double piston cylinder 230 comprises a first and second piston 231 , 232 inside a housing 239. A pump chamber 233 is formed in between these pistons 231 , 232. The pump chamber 233 is an air-chamber which can be compressed. The pump chamber 233 comprises a pump spring 234. The pump spring 234 in the pump chamber acts on both the first and second piston. The pump spring 234 pushes the pistons 231 , 232 away from each other to expand the pump chamber 233.

The pump chamber 233 has a first port which is provided with an inlet check valve 236 which allows a fluid flow into pump chamber 233 and a second port provided with an outlet check valve 237 which allows a fluid flow out of the pump chamber 233 via the conduit 202 to the pneumatic cylinder 220. The inlet check valve 236 provides an air connection to the environment. Further, the second port is fluidly connected to a safety relief valve 238 to limit a maximum pressure occurring in the pump chamber 233. Fig. 5 shows a re-establishment to the operational state of the vehicle door operating system 1 after an emergency situation has occurred. During the emergency situation, the relief valve 227 was opened and the pneumatic cylinder 220 was depressurised. Now, to return to the operational state, the pneumatic cylinder 220 has to be pressurised again.

First, the relief valve 227 is closed. A manually single acting relief valve is normally closed (when not operated). Subsequently, the pneumatic cylinder 220 is pressurised again by the double piston cylinder 230. The double piston cylinder 230 is part of the emergency circuit 200 to restore pneumatic pressure to the pneumatic cylinder 220. The pump chamber 233 of the double piston cylinder 230 is fluidly connected by a pneumatic conduit 202 to the pressure chamber 221 of the pneumatic cylinder 220. By compressing the pump chamber 233 of the reset cylinder 230, a fluid flow is generated via the pneumatic conduit 202 to the pressure chamber 221 of the pneumatic cylinder 220.

As shown in Fig. 5 by the arrows, in a step during the re-establishment, the pump unit 20 is driven to pressurise the push chamber 122 of the hydraulic cylinder 10. At the same time, the reset chamber 235 is pressurised via a conduit 203 (indicated by an arrow). The conduit 203 extends in between the push chamber 122 of the hydraulic cylinder 10 and the reset chamber 235 of the double piston cylinder 230. The conduit 203 includes a reset valve 212 which is operated by the pneumatic cylinder 220. As the emergency valve 210, the reset valve 212 is open when the pneumatic cylinder 220 is depressurised. The reset valve 212 will be closed again when the pneumatic cylinder 220 is pressurised. So, after an opening of the pressure relief valve 227, the open reset valve 212 allows a fluid flow through the conduit 203 to pressurise the reset chamber 235.

At the one hand, due to the fluid flow to the push chamber 122 during the re-establishment of the vehicle door operating system to the operational state, the door may be moved by the door actuator 10 (as indicated by an arrow in Fig. 5) to the full open position. Generally, in an emergency situation, a door will already be moved to the full open position, such that a pressurising of the push chamber 122 of the hydraulic cylinder 10 will not generate a movement of the door.

Additionally, as further shown in Fig. 5, due to the fluid flow to the reset chamber 235, both pistons 231 , 232 of the double piston cylinder 230 are moving outwardly. The second piston 232 will move until the piston 232 is blocked. The first piston 231 will move as long as the reset chamber 235 is pressurised. When the second piston 232 is blocked and the first piston 231 is still moving, the pump chamber 233 is compressed. The compression of the pump chamber 233 renders an increase in pressure. As the pump chamber 233 is fluidly connected with the pressure chamber of the pneumatic cylinder 220, the pneumatic cylinder 220 is also pressurised. Here, the optional pressure safety relief valve 238 prevents an overload of the pneumatic cylinder 221.

As shown in Fig. 6, the increase in pressure in the pressure chamber 221 of the pneumatic cylinder 220 will result in a closure of the reset valve 212. After closing the reset valve 212, the reset chamber 235 is no longer pressurised by the pump unit 20. The pump spring 234 inside the pump chamber 233 is compressed during the opening of the reset valve 212. The pump spring 234 exerts a spring force onto the first piston 231. After closing the reset valve 212 and due to a lowering of pressure in the reset chamber 235 (due to a back flow along a throttle 25), the spring 234 will cause a movement of the first piston 231 away from the second piston 232. Hence, the first piston will return to an initial position.

Further, Fig. 6 illustrates that the double piston cylinder 230 cooperates with the hydraulic cylinder 10. A cooperation is provided by a connection of the second piston 232 with the piston rod 13 of the hydraulic cylinder 10. A movement of the piston rod 13 will cause a movement of the second piston 232 via the piston rod 232'. The movement of the second piston 232 will introduce a movement of the first piston 231. The pressure in the reset chamber 235 will lower as a result of a back flow of fluid from the reset chamber 235 via a conduit 204 to the reservoir 24 of the combined circuit 100,200. The conduit 204 comprises a throttle 25 which is configured to control a pressurising in a first step to re-establish the operational state of the vehicle door operating system 1 and in a next step to control a de-pressurising of the reset chamber 235 to return the reset cylinder 230 to an initial state. The throttle 25 is preferably a passive throttle and embodied as an orifice. Due to the movement of the first piston 231 in a direction away from the second piston 232, the pressure inside the pump chamber 233 will be reduced. The outlet check valve 237 prevents a pressure reduction in the fluidly connected pressure chamber 221 of the pneumatic cylinder 220. Hence, the reset-cylinder returns to an initial state, the pneumatic cylinder remains in position for an operational state and both the reset valve 212 and the emergency valve 210 remain in the closed position.

Fig. 6 shows a close to full open, e.g. 80%, and Fig. 7 shows a full open position of the door actuated by the hydraulic cylinder 10. As shown in Fig. 6, during the re-establishment, the second piston 232 is initially blocked at a position Pi which corresponds with an intermediate door position close to the full open position of the door. Here, the position Pi is an end- stroke position of the piston 232 in the housing 239 of the reset cylinder 230. A further movement of the piston rod 13 of the hydraulic cylinder 10 will move the door to the full open position. At the same time, due to the connection between the piston rod 13 and the second piston 232, the further movement of the piston rod 13 will move the second piston 232. The second piston 232 will be retracted into the housing 239 of the double piston cylinder 230 to a position Po, see Fig. 7. This finally obtained retracted position Po of the second piston 232 corresponds with a full open position of the vehicle door.

As shown in Fig. 5-6, the piston rod 13 of the hydraulic cylinder 10 is connected to the piston rod 232' of the second piston 232 by an abutting engagement. The hydraulic cylinder 10 is connected to double piston cylinder 230, such that the piston rod 232' can be pushed into the housing 239. Here, the abutting engagement is positioned in between the rack 191 of the door moving mechanism 190 and the piston rod 232'. The rack 191 is aligned with the piston rod 232' of the double piston cylinder 230. The rack 191 is linearly movable over a stroke. At an initial stage of the stroke (corresponding with initially closed doors), the rack 191 does not engage the piston rod 232' of the double piston cylinder. At an end stage of the stroke of the rack 191 , the rack 191 abuts and contacts the piston rod 232'. A further movement of the rack, will push and move the piston rod 232' into the housing 239. Fig. 8 shows in a schematic view an alternative embodiment of the vehicle door operating system 1.

A first difference in comparison with the embodiment as shown in Fig. 3-7 considers the positioning of the non-return valve 21 1 which is here positioned in between the pull chamber 121 of the hydraulic cylinder 10 and the emergency valve 210 which is operated by the pneumatic cylinder 220. The non-return valve 21 1 is positioned in fluid connection with the conduit 101. A second difference in comparison with the embodiment as shown in figures 3-7 relates to the configuration of the first piston 231. Here, the first piston 231 has a first piston surface directed to the reset chamber 235 which is smaller than a second piston surface directed to the pump chamber 233. The first piston 231 comprises a piston shaft 231.0 in between a first and second piston portion 231.1 , 231.2 which piston portions respectively form the first and second piston surface. The first piston surface operates in an hydraulic environment. The second piston surface operates in a pneumatic environment.

A third difference in comparison with the embodiment as shown in figures 3-7 relates to the configuration of the housing of the double piston cylinder 230. Here, the housing 239 is subdivided into two separate sub-housings 239.1 , 239.2. The separate sub-housings allow a spatial placement of the sub-housings away from each other which is a benefit in narrow build-in spaces.

The pump chamber 233 is subdivided into two separate pump sub-chambers 233.1 , 233.2. The sub-chambers are fluidly interconnected. Each sub-chamber has its own inlet check valve 236.1 , 236.2 and its own outlet check valve 237.1 , 237.2. Optionally, the sub- chambers are fluidly connected to a common safety relief valve 238.

The pump sub-chamber 239.2 has a smaller diameter in cross-section than the pump sub- chamber 239.1 to enlarge a stroke of movement of the second piston 232. A displacement of the first piston 231 is multiplied due to the reduction in diameter of the second pump sub- chamber 239.2.

Fig. 9 shows a schematic view of the vehicle door operating system 1 including at least one lock cylinder 30. The lock cylinder 30 is a single acting hydraulic cylinder. The lock cylinder 30 serves to lock and unlock a vehicle door 18. When pressurised, the lock cylinder 30 extends to a lock position and when de-pressurised, the lock cylinder 30 retracts to an unlock position.

In the operational state, the lock cylinder 30 is operated by a lock valve 31. The lock valve 31 is a control valve which is controlled by the control unit. In case of an emergency, the lock cylinder 30 is de-pressurised by opening a lock emergency valve 32.

Here, the lock emergency valve 32 is operated together with the emergency valve 210 by the pneumatic cylinder 220. The emergency valve 210, the reset valve 212 and the lock emergency valve 32 are integrated in a common valve housing 210'. The valve housing 210' has a first, second and a third channel 201 ', 212', 205' for conducting a hydraulic fluid. The first, second and third channel are arranged in parallel. The channels are oriented in perpendicular with a mounting surface for mounting the pneumatic cylinder 220. A borehole forms an intersecting channel 224' which intersects the first, second and third channel. The intersecting channel 224' originates from the mounting surface and extends through the first, second and third channel. A closure element 224 is movable positioned in the intersecting channel 224'to open or close the crossing channels. The closure element 224 is connected to the pneumatic cylinder 220. By actuating the pneumatic cylinder 220, the closure element is movable to an open or closed position in which each channel is respectively open or closed.

An outlet port of the lock emergency valve 32 is fluidly connected with the reservoir 24 of the hydraulic circuit 100. The locking emergency valve 32 is fluidly connected with the reservoir 24 by a lock conduit 205.

Further, a non-return valve 33 is positioned in a conduit 104 originating from the first conduit 101 (in between the pump unit 20 and the pull chamber of the hydraulic cylinder 10) and extending to the lock cylinder 30. The conduit 104 is branched twice at a point in between the non-return valve 33 and the lock cylinder 30 into a conduit 105 including the lock valve 31 and a conduit 205 including the lock emergency valve 32. Optionally, the conduit 104 comprises a second lock valve to allow successive movements of actuators.

Fig. 10 shows in a schematic view an alternative embodiment of the vehicle door operating system 1 according to the invention. The vehicle door operating system 1 comprises a hydraulic circuit 100 as shown in fig. 1. The vehicle door operating system 1 comprises a door actuator operating a vehicle door 18 of a vehicle 17. Here, the door actuator is a double-acting hydraulic cylinder 10. The hydraulic cylinder 10 is a linear cylinder to provide a linear movement. The hydraulic cylinder comprises a housing 1 1 which is subdivided by a piston 12 into a first chamber, also called a pull chamber 121 and a second chamber, also called a push chamber 122. At a side of the pull chamber 121 , the piston 12 is connected to a piston rod 13 which extends in an axial direction. A distal end of the piston rod 13 is connected to a vehicle door operating mechanism 19, which is here rack and pinion mechanism. The piston rod 13 is connected to a rack 191 of the rack and pinion mechanism. The rack 191 is connected to a pinion 192. The piston rod 13 is outwardly and inwardly movable to respectively open and close a vehicle door 18. The rack and pinion mechanism converts a linear movement provided by the door actuator 1 to a rotating movement. The rack and pinion mechanism is connectable to a rotatable member of a vehicle door assembly to operate a movement of a vehicle door 18. The vehicle door is in particular a swing door of a public passenger bus.

The door actuator is operatable by a control unit (not shown). The control unit is

electronically connected to a hydraulic actuating circuit 100 for hydraulically operating the door actuator.

The door actuator is operatively connected to a pump unit 20. The pump unit 20 comprises a bi-directional pump 21 and a pump motor 22. The bi-directional pump 21 is driveable in two directions (clockwise and counter-clockwise) to operate the double-acting hydraulic cylinder 10. A first pump port 21.1 of the pump 21 is hydraulically connected by a hydraulic conduit 101 to the pull chamber 121. A second pump port 21.2 of the pump 21 is hydraulically connected by a hydraulic conduits 102 to the push chamber 122. A pilot operated check valve 21.3, 21.4, here a pressure operated check valve POCV1 , POCV2, is provided in between each pump port 21.1 , 21.2 and the hydraulic cylinder.

Further, the pump unit 20 comprises a shuttle valve 23 and a reservoir 24. The hydraulic actuating circuit 100 comprises at least one pressure safety valve RV1 , RV2 to prevent an overload of the hydraulic circuit 100. Such a configuration of a pump unit 20 is generally known.

Fig. 10 shows the actuating circuit 100 as shown in fig. 2 which circuit is extended with an emergency circuit 200. The piston rod 13 of the hydraulic cylinder 10 is shown in a retracted position which corresponds with a connected vehicle door in a closed position. The circuit as shown in Fig. 10 represents an operational state of the vehicle door operating system. In the operational state, a door of the vehicle door operating system can be operated from the open to the closed position and vice versa. In Fig. 10, the hydraulic cylinder 10 is stably kept in position by a hydraulic pressure in the pull and push chambers 121 , 122.

The emergency circuit 200 serves to allow a manual opening of the vehicle door in case of an emergency. The vehicle door which may be initially in the closed position can be opened by a passenger or by someone standing outside the vehicle when releasing hydraulic pressure inside the hydraulic cylinder 10.

To release the hydraulic pressure, a bypass conduit 201 is provided. The bypass conduit 201 extends in between the pull and push chamber 121 , 122 of the hydraulic cylinder 10. The bypass conduit 201 is here connected to the hydraulic conduit 101 which extends to the pull chamber 121 and the hydraulic conduit 102 which extends to the push chamber 122 of the hydraulic cylinder 10. The bypass conduit 201 comprises a valve 210 which is closed during the operational state of the vehicle door operating system 1.

Further, the bypass conduit 201 comprises a non-return valve 21 1 which prevents a fluid flow from the push chamber 122 to the pull chamber 121 of the hydraulic cylinder 10. Here, the non-return valve 211 is positioned in between the emergency valve 210 and the closed chamber 122, but the non-return valve 21 1 can also be positioned at the other side of the emergency valve 210 in between the emergency valve 210 and the pull chamber 121.

In case of an emergency, the emergency valve 210 can be opened. Here, the emergency valve 210 is adapted to be operated by a single-acted pneumatic cylinder 220. In the operational state of the vehicle door operating system, the pneumatic cylinder is

pressurised. When pressurised, the pneumatic cylinder 220 keeps the emergency valve 210 in a closed position. The bypass-conduit 201 remains closed. When the pneumatic cylinder 220 is de-pressurised, the emergency valve 210 is operated and moved from a closed to an open position. The pneumatic cylinder 220 can be de-pressurised by manually opening a relief valve 227. The relief valve 227 is fluidly connected with a pressure chamber 221 of the pneumatic cylinder 220 to de-pressurise the pneumatic cylinder in case of emergency. The pressure chamber 221 is positioned at one side of a piston 222 of the pneumatic cylinder 220. A spring 223 acts on the opposite side of the piston 222 to counteract the pressure chamber 221. The spring 223 exerts a spring force to de-pressurise the pressure chamber 221 and retract the piston 222. Here, the relief valve 227 is a manually operated relief valve which has a switch. The switch is adapted to be manually operated e.g. by pressing a button or handling a bar by a person.

As shown in Fig. 10, the emergency circuit 200 comprises a reset cylinder 230. The reset cylinder 230 is arranged to reset the emergency valve 210 to the operational state. The reset cylinder 230 comprises a housing 239 and a piston 231. The piston 231 is positioned inside the housing 239 and subdivides the housing into a reset chamber 235 and a pump chamber 233. The reset chamber 235 is a hydraulic chamber. The reset chamber 235 is positioned at one side of the piston 231 and the pump chamber 233 is positioned at an opposite side of the piston 231. The piston 231 separates the pump chamber 233 from the reset chamber 235.

Here, the piston 231 is embodied as the first piston in Fig. 8. The first piston 231 has a first piston surface directed to the reset chamber 235 which is smaller than a second piston surface directed to the reset chamber 233. The piston 231 comprises a piston shaft 231.0 in between a first and second piston portion 231.1 , 231.2 which piston portions respectively form the first and second piston surface. The first piston surface operates in an hydraulic environment. The second piston surface operates in a pneumatic environment.

The pump chamber 233 is a pneumatic chamber, an air-chamber which can be pressurised. A pump spring 234 is positioned inside the pneumatic chamber 233 and exerts a spring force onto the piston 231 to move the piston 231 towards the reset chamber 235.

The pump chamber 233 has a first port which is provided with an inlet check valve 236 which allows a fluid flow into pump chamber 233 and a second port provided with an outlet check valve 237 which allows a fluid flow out of the pump chamber 233. The inlet check valve 236 provides a fluid connection to the environment. The outlet check valve 237 is fluidly connected to a safety relief valve 238 to limit a maximum pressure occurring in the pump chamber 233. After an emergency situation, the pressure relief valve 227 is opened and a pressure is released from the pressure chamber 221 of the pneumatic cylinder 220 via the conduit 202. To return the vehicle door operating system back to the operational state, it is necessary to pressurise the pneumatic cylinder 220 again to close the emergency valve 210 and the reset valve 212.

First, the relief valve 227 is closed. A manually single acting relief valve is normally closed. Subsequently, the pneumatic cylinder 220 is pressurised again by the reset cylinder 230. The reset cylinder 230 is part of the emergency circuit 200 to restore pneumatic pressure to the pneumatic cylinder 220. The pump chamber 233 of the reset cylinder 230 is fluidly connected by the conduit 202 to the pressure chamber 221 of the pneumatic cylinder 220. By compressing the pump chamber 233 of the reset cylinder 230, a fluid flow is generated via the conduit 202 to the pressure chamber 221 of the pneumatic cylinder 220.

As also shown in Fig. 5, in a step during the re-establishment, the pump unit 20 is driven to pressurise the push chamber 122 of the hydraulic cylinder 10. At the same time, the reset chamber 235 is pressurised via a conduit 203 (indicated by an arrow). The conduit 203 extends in between the push chamber 122 of the hydraulic cylinder 10 and the reset chamber 235 of the reset cylinder 230. The conduit 203 includes a reset valve 212 which is operated by the pneumatic cylinder 220. As the emergency valve 210, the reset valve 212 is open when the pneumatic cylinder 220 is depressurised. The reset valve 212 will be closed again when the pneumatic cylinder 220 is pressurised. So, after an opening of the pressure relief valve 227, the open reset valve 212 allows a fluid flow through the conduit 203.

Due to the fluid flow from the pump unit 20 to the reset chamber 235, the piston 231 will move and the pump chamber 233 will be compressed. By compressing the pump chamber 233, a fluid flow will be generated to the pressure chamber 221 of the pneumatic cylinder 220. Due to the fluid flow, the pneumatic cylinder 220 will be pressurised again which will operate the emergency valve 210 and the reset valve 212 from the open to the closed position. The optional pressure safety relief valve 238 prevents an overload of the pneumatic cylinder 221. As also shown in Fig. 6, the increase in pressure in the pressure chamber 221 of the pneumatic cylinder 220 will result in a closure of the reset valve 212. After closing the reset valve 212, the reset chamber 235 is no longer pressurised by the pump unit 20. The pump spring 234 inside the pump chamber 233 was compressed during the opening of the reset valve 212. The pump spring 234 is exerting a spring force onto the first piston 231. After closing the reset valve 212 and due to a lowering of hydraulic pressure in the reset chamber 235, the pump spring 234 will cause a movement of the piston 231.

The pressure in the reset chamber 235 will lower as a result of a back flow of fluid from the reset chamber 235 via the conduit 204 to the reservoir 24 of the circuit 100,200. The conduit 204 comprises a throttle 25 which is configured to control a pressurising in a first step and subsequently de-pressurising of the reset chamber 235 in a next step. The throttle 25 is preferably a passive throttle and embodied as an orifice. Due to the retracting movement of the first piston 231 , the pressure inside the pump chamber 233 will be reduced. The outlet check valve 237 prevents a pressure reduction in the fluidly connected pressure chamber 221 of the pneumatic cylinder 220. Hence, the pneumatic cylinder remains in position and both the reset valve 212 and the emergency valve 210 remain in the closed position, while the reset cylinder 230 returns to an initial state.

Fig. 1 1 shows a schematic view of an emergency valve assembly which incorporates both an emergency valve and a reset valve. The emergency valve assembly comprises a valve housing 210' including at least a first and second channel 201 ',212'. The first and second channels extend through the valve housing 210' from one side to an opposite side. Further, the valve housing 210' includes an intersecting channel 224' which intersects the first and second channel. The intersecting channel is arranged for receiving a closure element 224. The closure element 224 is movable positioned inside the intersecting channel. The closure element 224 is connectable to a pneumatic cylinder 220. The valve housing 210' has a mounting surface for mounting the pneumatic cylinder 220. A movement of the closure element 224 provides an opening or closing of the first and second channel to function respectively as an emergency valve 210 and a reset valve 212.

Besides the illustrated embodiments, numerous variants are possible. In a variant of the illustrated embodiment of the vehicle door operating system may be arranged for operating other vehicle door types, e.g. a train or automotive door.

It is noted that the term "comprising" (and grammatical variations thereof) is used in this specification in the inclusive sense of "having" or "including", and not in the exclusive sense of "consisting only of".

Features and aspects described for or in relation with a particular embodiment may be suitably combined with features and aspects of other embodiments, unless explicitly stated otherwise.

Thus, the invention provides a vehicle door operating system comprising an emergency circuit including a reset cylinder which may operate independent from an air supply system of a passenger bus. The vehicle door operating system comprises a hydraulic actuating circuit and an emergency circuit. The actuating circuit comprises a double acting hydraulic cylinder as a door actuator for driving a door mechanism . The emergency circuit comprises a by-pass conduit which is connected with an emergency valve. The emergency valve can be opened by manually operating a relief valve which causes a depressurising of a single acting pneumatic cylinder which is operatively connected to the emergency valve. Further, the emergency circuit comprises a reset cylinder including a pneumatic pump chamber for resetting the system to an operational state after an occurrence of an emergency situation. Reference signs list:

30 lock cylinder

1 vehicle door operating system 31 lock valve

32 lock emergency valve

10 hydraulic cylinder 33 non-return valve

1 1 housing

12 piston 100 hydraulic actuating circuit

121 pull chamber 101 first conduit to pull chamber

122 push chamber 102 second conduit to push chamber

13 piston rod

200 emergency circuit

17 vehicle; transit bus 201 bypass conduit

170 vehicle floor 201 ' first channel

171 vehicle chassis 202 pneumatic conduit to pneumatic

18 vehicle door cylinder

19 vehicle door operating mechanism 203 hydraulic conduit to reset cylinder

191 rack 204 branch conduit to reservoir

192 pinion 205 lock conduit to reservoir

193 upright shaft 205' third channel

194 shaft flange 210 emergency valve

195 shaft arm 210' valve housing

196 slider

21 1 non-return valve

20 pump unit 212 reset valve

21 pump 212' second channel

21.1 first pump port 220 pneumatic cylinder

21.2 second pump port 221 pressure chamber

21.3 check valve 222 piston

21.4 check valve 222' piston rod

22 pump motor 223 spring

23 shuttle valve 224 closure element

24 reservoir 224' intersecting channel

25 throttle 227 pressure relief valve 230 reset cylinder, double piston cylinder

231 first piston

231.0 piston shaft

231.1 first piston portion

231.2 second piston portion

232 second piston

233 pump chamber

233.1 central sub-chamber

233.2 central sub-chamber

234 pump spring

235 reset chamber

236 inlet check valve

237 outlet check valve

236.1 inlet check valve

236.2 inlet check valve

237.1 outlet check valve

237.2 outlet check valve

238 safety relief valve

239 housing

239.1 sub-housing

239.2 sub-housing

239.3 proximal housing end face

239.4 distal housing end face

POCV1 first pressure operated check valve

POCV2 second pressure operated check valve

RV1 first relief valve

RV2 second relief valve