Technical field

The present invention relates to a guide arrangement for guiding a moveable carriage along a vertical guide rail of an elevator, as defined in independent claims 1 and 4. The invention further relates to a carriage for moving objects along a vertical guide rail of an elevator. The invention also concerns the use of such a carriage and a method for constructing a guide rail for an elevator, as defined in the other independent claims.

Background

Most elevators are provided with vertical guide rails, which are used for guiding an elevator car and a counterweight. Often an elevator is provided with own guides rail for both the elevator car and the counterweight. The guide rails run in the vertical direction from the bottom to the top of the elevator shaft. Typically, each guide rail consists of several vertical segments. The guide rails are assembled by connecting those segments to each other on-site. A typical guide rail has a T-shaped cross-sectional profile. The arms of the profile are used for attaching the guide rail to the elevator shaft, often via guide rail brackets. The stem of the profile forms a nose that functions as support surfaces for the elevator car or the counterweight. Typically, each of the elevator car and the counterweight is supported between a pair of opposite guide rails.

The guide rails can be utilized also during the construction phase of an elevator. For instance, the guide rails can guide a moveable platform or lifting device that is used for lifting components needed for the elevator. For instance, the assembly of the guide rails can be started from the bottom of the elevator shaft and the already assembled portions of the guiderails can be used for guiding a lifting device that is used for lifting guide rail segments for assembly. Such a lifting device can be supported between a pair of guide rails. However, that requires simultaneous assembly of both guide rails.

Supporting of a lifting device against a single guide rail is challenging. Because the guide rails are attached to the walls of the elevator shaft, it is not possible to use guiding means that are engaged with the backside of the guide rail. The guiding means can thus be engaged only with the stem of a T-profile guide rail. The force exerted on a lifting device by a lifting rope and gravitation tends to turn the lifting device on the guide rail, which leads to a risk of derailing of the lifting device.

Summary

An object of the present invention is to provide an improved guide arrangement for guiding a moveable carriage along a vertical guide rail of an elevator, the carriage being configured to be moveable by means of at least one hoisting member and the guide rail comprising a first support surface extending in the vertical direction and a second support surface that is parallel to the first support surface and faces an opposite direction, wherein the vertical direction defines a first direction, a horizontal direction perpendicular to the first and the second support surfaces defines a second direction, and the direction perpendicular to the first direction and the second direction defines a third direction. The characterizing features of the guide arrangement according to the invention are given in claims 1 and 4. Another object of the invention is to provide an improved method for constructing a guide rail for an elevator. The characterizing features of the method are given in another independent claim. Further objects of the invention are to provide an improved carriage for moving objects along a vertical guide rail of an elevator and the use of such a carriage for lifting objects in an elevator shaft.

The guide arrangement according to the invention comprises a frame, a first pair of guide wheels connected to the frame and comprising a first guide wheel that is configured to roll on the first support surface of the guide rail and a second guide wheel that is configured to roll on the second support surface of the guide rail opposite to the first guide wheel, wherein each of the first guide wheel and the second guide wheel is configured to be pivotable about a pivot axis that is in a use position of the guide arrangement parallel to the second direction and located in the third direction at a distance from an imaginary center plane of the guide wheel, wherein the guide arrangement is configured to allow the first guide wheel and the second guide wheel to turn from the direction, in which the imaginary center plane of the guide wheel is parallel to the first direction, only over a limited angle to each direction about the pivot axis, a first limiter element connected to the frame and being located in the use position of the guide arrangement below the first pair of guide wheels, and a second limiter element connected to the frame and being located in the use position of the guide arrangement above the first pair of guide wheels, wherein each of the first and the second limiter elements is configured to cooperate with a surface of the guide rail to limit the movement of the guide arrangement in the third direction towards the guide rail, and the guide arrangement is configured to exert via the first guide wheel and the second guide wheel on the first and the second support surfaces a force acting in the second direction.

In an alternative configuration, the guide arrangement comprises said frame and said first pair of wheels and furthermore a second pair of guide wheels connected to the frame and comprising a third guide wheel that is configured to roll on the first support surface of the guide rail and a fourth guide wheel that is configured to roll on the second support surface of the guide rail opposite to the third guide wheel, wherein each of the third guide wheel and the fourth guide wheel is configured to be pivotable about a pivot axis that is in a use position of the guide arrangement parallel to the second direction and located in the third direction at a distance from an imaginary center plane of the guide wheel, wherein the guide arrangement is configured to allow the third guide wheel and the fourth guide wheel to turn from the direction, in which the imaginary center plane of the guide wheel is parallel to the first direction, only over a limited angle to each direction about the pivot axis, and a first limiter element connected to the frame and being located between the first pair of guide wheels and the second pair of guide wheels, wherein the first limiter element is configured to cooperate with a guide surface of the guide rail to limit the movement of the guide arrangement in the third direction towards the guide rail and the guide arrangement is configured to exert via the third guide wheel and the fourth guide wheel on the first and the second support surfaces a force acting in the second direction.

The guide arrangement according to the invention thus comprises at least a first pair of guide wheels and at least one limiter element. In addition, the guide arrangement comprises at least a second pair of guide wheels or a second limiter element.

In the guide arrangement according to the invention, the guide wheels are thus allowed to turn to a limited extent. Because the guide wheels are compressed against the support surfaces of the guide rail, the friction between each guide wheel and the respective support surface of the guide rail creates a counter force for a gravitational force or lifting force acting on the guide arrangement. Because the pivot axes of the wheels are located at a distance from the center planes of the wheels, the force turns the guide wheels about the pivot axes. When the guide arrangement moves upwards, the upper edges of the guide wheels turn towards the guide rail, i.e. in a typical arrangement towards that wall of the elevator shaft to which the guide rail is attached. When the guide arrangement moves downwards, the lower edges of the guide wheels turn towards the guide rail. As the guide arrangement is guided in both moving directions towards the guide rail, derailing of the guide arrangement is effectively prevented. The limiter elements prevent moving of the guide arrangement in the third direction beyond a predetermined limit. The position of the guide arrangement is thus kept constant in the third direction. The limited turning angle of the guide wheels ensures that the guide wheels roll smoothly.

The guide arrangement allows supporting a carriage for lifting objects in an elevator shaft against a single guide rail. This allows, for instance, using two carriages in a single elevator shaft independently from each other.

The carriage according to the invention comprises a guide arrangement defined above.

The method according to the invention comprises the steps of

- attaching at least one guide rail element to a wall of an elevator shaft at a lower end of the elevator shaft to form an installed guide rail portion,

- arranging a carriage defined above on the installed guide rail portion,

- using the carriage to lift a guide rail element to an upper end of the installed guide rail portion,

- attaching the lifted guide rail element to the wall of the elevator shaft above the installed guide rail portion.

The method according to the invention allows utilizing an already installed guide rail portion for installing the guide rail elements above the installed guide rail portion. Two guide rails can be installed independently from each other.

According to an embodiment of the invention, the guide arrangement comprises a second pair of guide wheels connected to the frame and comprising a third guide wheel that is configured to roll on the first support surface of the guide rail and a fourth guide wheel that is configured to roll on the second support surface of the guide rail opposite to the third guide wheel, wherein each of the third guide wheel and the fourth guide wheel is configured to be pivotable about a pivot axis that is in a use position of the guide arrangement parallel to the second direction and located in the third direction at a distance from an imaginary center plane of the guide wheel, the guide arrangement is configured to allow the third guide wheel and the fourth guide wheel to turn from the direction, in which the imaginary center plane of the guide wheel is parallel to the first direction, only over a limited angle to each direction about the pivot axis, the second pair of guide wheels being positioned in the use position of the guide arrangement below the first limiter element and the guide arrangement being configured to exert via the third guide wheel and the fourth guide wheel on the first and the second support surfaces a force acting in the second direction. The second pair of guide wheels increases the force keeping the guide arrangement in contact with the guide rail.

According to an embodiment of the invention, the guide arrangement is configured to allow the first guide wheel and the second guide wheel to turn at most 5 degrees, preferably at most 2 degrees to each direction about the pivot axis.

According to an embodiment of the invention, the guide arrangement is configured to allow the third guide wheel and the fourth guide wheel to turn at most 5 degrees, preferably at most 2 degrees to each direction about the pivot axis.

By limiting the turning of the guide wheels to 5 or 2 degrees, the guide wheels roll smoothly on the support surfaces. The turning could be limited to an even smaller angle, such as +/-1 degree from the first direction.

According to an embodiment of the invention, the guide arrangement further comprises a second limiter element connected to the frame and being located in the use position of the guide arrangement above the upper one of the two pairs of guide wheels, the second limiter element being configured to cooperate with a guide surface of the guide rail to limit the movement of the guide arrangement in the third direction towards the guide rail. According to an embodiment of the invention, the guide arrangement comprises a third limiter element connected to the frame and being located in the use position of the guide arrangement below the second pair of guide wheels, wherein the third limiter element is configured to cooperate with a guide surface of the guide rail to limit the movement of the guide arrangement in the third direction towards the guide rail.

Although the invention with two pairs of guide wheels would work with a single limiter element between the pairs of the guide wheels, limiter elements arranged below and/or above the guide wheels improve functioning of the guide arrangement,

According to an embodiment of the invention, the arrangement further comprises a fourth limiter element that is located between the second pair of guide wheels and the first limiter element, and the fourth limiter element is configured to cooperate with a guide surface of the guide rail to limit the movement of the guide arrangement in the third direction towards the guide rail.

According to an embodiment of the invention, the first pair of guide wheels, the first limiter element and the second limiter element are arranged in a first wheel assembly and the pivot axis of the first pair of guide wheels forms a common pivot axis about which the first wheel assembly can pivot. By arranging the guide wheels and the limiter elements in the same wheel assembly, it can be ensured that the components are positioned accurately in relation to each other. Less strict tolerances can be applied to other parts of the guide arrangement.

According to an embodiment of the invention, the first wheel assembly comprises a counterweight arranged in the third direction on opposite side of the pivot axis than the first pair of guidewheels. The counterweight facilitates turning of the first wheel assembly when the moving direction of the guide arrangement changes from upward movement to downward movement.

According to an embodiment of the invention, the second pair of guide wheels, the third limiter element and the fourth limiter element are arranged in a second wheel assembly and the pivot axis of the second pair of guide wheels forms a common pivot axis, about which the second wheel assembly can pivot. The second wheel assembly provides similar benefits as the first wheel assembly.

According to an embodiment of the invention, the second wheel assembly comprises a counterweight arranged in the third direction on opposite side of the pivot axis than the second pair of guidewheels. The counterweight facilitates turning of the second wheel assembly in the same way as in the first wheel assembly.

According to an embodiment of the invention, the limiter elements are configured to cooperate with a guide surface connecting the first support surface to the second support surface. The limiter elements can thus roll or slide on the end surface of the stem of a T-shaped guide rail profile.

According to an embodiment of the invention, the guide arrangement comprises means for adjusting the force acting on the support surfaces via the guide wheels. The greater the force acting on the support surfaces is, the better the guide arrangement is kept in contact with the support surfaces. On the other hand, that increases the rolling resistance of the guide wheels. With the force adjusting means, the force can be optimized.

According to an embodiment of the invention, the limiter elements comprise limiter wheels. The limiter wheels minimize the moving resistance caused by the limiter element.

According to an embodiment of the invention, the coefficient of friction between the guide wheels and the guide rail is configured to be at least 0.15. With a sufficient coefficient of friction, the guide arrangement is effectively kept in contact with the guide rail.

According to an embodiment of the invention, the carriage for moving objects along a vertical guide rail of an elevator is configured to lift guide rail elements for constructing a guide rail for an elevator.

According to an embodiment of the invention, the guide arrangement is configured to exert via the guide wheels on the guide rail a force, which is 0.5- 3 times the gravitational force acting on the carriage when the carriage is loaded with the maximum design load of the carriage. This ensures that the guide arrangement is kept in contact with the guide rail and the guide wheels pivot when the moving direction of the carriage changes.

Brief description of the drawings

Embodiments of the invention are described below in more detail with reference to the accompanying drawings, in which

Fig. 1 shows schematically an elevator shaft and carriages according to an embodiment of the invention,

Fig. 2. shows a side view of a carriage according to an embodiment of the invention,

Fig. 3 shows a front view of the carriage of Fig. 2,

Fig. 4 shows a partial view of the carriage of Fig. 2 moving upwards,

Fig. 5 shows a partial view of the carriage of Fig. 2 moving downwards,

Fig. 6 shows a wheel assembly according to an embodiment of the invention,

Fig. 7 shows a wheel assembly according to another embodiment of the invention,

Fig. 8 shows a cross-sectional view of a guide arrangement according to an embodiment of the invention,

Fig. 9 shows as a flowchart the method according to the invention,

Fig. 10 shows a detail of the carriage according to an embodiment of the invention, and

Fig. 11 shows a detail of the carriage according to another embodiment of the invention.

Detailed description of embodiments of the invention

Figure 1 shows schematically an elevator shaft 10. The elevator shaft 10 is provided with guide rails 1 1 for guiding an elevator car and/or a counterweight of the elevator. The guide rails 1 1 run in the elevator shaft 10 in the vertical direction. Each guide rail 1 1 extends from a bottom part of the elevator shaft 10 to a top part. Each guide rail 1 1 is attached to a wall of the elevator shaft 10. The guide rails 1 1 could be attached directly to the wall, but in figure 1 the guide rails 1 1 are attached to the walls of the elevator shaft 10 via brackets. Figure 1 shows two guide rails 1 1 . Each guide rail 1 1 is made of several guide rail elements 1 1 a. One of the guide rails 1 1 is fully installed and one of the guide rails 1 1 is under construction.

Figure 1 shows two carriages 1 . Each carriage 1 is arranged on one of the guide rails 1 1 . The carriages 1 are configured to be moveable in the vertical direction along the guide rails 1 1 . Each carriage 1 is configured to be lifted by means of at least one hoisting member 20. The hoisting member 20 can be, for instance, a wire, such as a steel wire, a belt, such as a toothed belt or a flat belt, or a coated rope. Each hoisting member 20 is operated by means of a motor 21 . The motor 21 is preferably an electric motor. The motor 21 can be operated at least for lifting the carriage 1 . The carriage 1 could be configured to move downwards by gravity, when any brake acting on the motor 21 , the hoisting member 20 and/or the carriage 1 is released. However, the motor 21 could also be operated to lower the carriage 1 .

Figures 2 to 8, 10 and 1 1 show different views of a guide arrangement and a carriage 1 according to embodiments of the invention. Figures 2 to 5, 8,10 and

1 1 show part of a guide rail 11 , which is compatible with the guide arrangement according to the invention.

The guide rail 1 1 comprises a first support surface 12a, which extends in the vertical direction. The guide rail 11 further comprises a second support surface 12b. The second support surface 12b is parallel to the first support surface 12a and faces an opposite direction. The vertical direction is hereinafter also referred to as a first direction A. In the example of the figures, the guide rail 11 has a T-shaped cross-section. The guide rail 1 1 thus has a stem and two arms 13. The first and the second support surfaces 12a, 12b are arranged on opposite surfaces of the stem. The surface 12c connecting the first and second support surfaces 12a, 12b forms a guide surface for the guide arrangement. The guide rail 1 1 is attached to the walls of the elevator shaft via the arms 13 of the profile. It is not necessary that the guide rail 11 has a T-profile. The first and the second support surfaces 12a, 12b could also be opposite surfaces of for example an l-shaped or rectangular profile. A horizontal direction that is perpendicular to the first and the second support surfaces 12a, 12b is hereinafter referred to as a second direction B. A horizontal direction that is perpendicular to both the vertical direction and the second direction B is hereinafter referred to as a third direction C.

The guide arrangement according to the invention comprises a frame 3. The frame 3 can be made of, for instance, steel plates and steel profiles. The frame 3 can thus comprise several parts that are attached to each other for example by welding and/or by means of suitable fastening elements, such as screws, bolts and nuts.

The guide arrangement further comprises a first pair of guide wheels 4. The first pair of guide wheels comprises a first guide wheel 4a and a second guide wheel 4b. The first guide wheel 4a is configured to roll on the first support surface 12a of the guide rail 1 1 and the second guide wheel 4b is configured to roll on the second support surface 12b of the guide rail 1 1 opposite to the first guide wheel 4a. In case of a T-shaped guide rail 1 1 , the guide wheels 4a, 4b are thus arranged on opposite sides of the stem of the guide rail profile.

The first guide wheel 4a and the second guide wheel 4b are pivotable about a pivot axis 5. In a use position of the guide arrangement, the pivot axis 5 is parallel to the second direction B. The pivot axis 5 is located in the third direction C at a distance from an imaginary center plane D of the guide wheels 4a, 4b. The center plane D refers to a plane that crosses the outer perimeter of the guide wheel 4a, 4b in the middle of the outer perimeter in the direction of the rotation axis of the guide wheel 4a, 4b.

The guide arrangement further comprises a first limiter element 6 connected to the frame 3 and being located in the use position of the guide arrangement below the first pair of guide wheels 4, and a second limiter element 7 connected to the frame 3 and being located in the use position of the guide arrangement above the first pair of guide wheels 4. Each of the first and the second limiter elements 6, 7 is configured to cooperate with a guide surface 12c of the guide rail 1 1 to limit the movement of the guide arrangement in the third direction C towards the guide rail 11 . In the example of the figures, the guide surface 12c is the surface connecting the first and second support surfaces 12a, 12b. However, the guide surface could also be another surface. The guide arrangement is configured to exert a force acting in the second direction B on the first and the second support surfaces 12a, 12b via the first guide wheel 4a and the second guide wheel 4b. The guide wheels 4a, 4b are thus pressed against the support surfaces 12a, 12b of the guide rail 1 1 .

The guide wheels 4a, 4b can roll along the guide rail 1 1 in the vertical direction. The guide wheels 4a, 4b thus allow lifting and lowering of the carriage 1 . For moving the carriage 1 in the third direction, the friction force created by the compression of the guide wheels 4a, 4b against the contact surfaces 12a, 12b should be overcome. The guide wheels 4a, 4b thus keep the carriage 1 in contact with the guide rail 1 1 .

When the carriage 1 is lifted by means of the hoisting member 20, the rolling resistance of the guide wheels 4a, 4b resist the movement. This creates a force which turns the guide wheels 4a, 4b about the pivot axis 5. The guide wheels 4a, 4b thus turn so that the upper edges turn towards the guide rail 1 1 , i.e. towards the arms 13 of the guide rail profile. As the carriage 1 moves upwards, the guide wheels 4a, 4b steer the carriage 1 towards the guide rail 1 1 . However, the second limiter element 7 cooperating with the guide surface 12c of the guide rail 1 1 limits moving of the carriage 1 towards the guide rail 1 1 . The position of the carriage 1 in the third direction C is thus maintained constant.

When the carriage 1 is lowered, the rolling resistance of the guide wheels 4a, 4b resist the movement. This creates a force which turns the guide wheels 4a, 4b about the pivot axis 5. The guide wheels 4a, 4b thus turn so that the lower edges turn towards the guide rail 1 1 . As the carriage 1 moves downwards, the guide wheels 4a, 4b steer the carriage 1 towards the guide rail 1 1 . However, the first limiter element 6 cooperating with the guide surface 12c of the guide rail 1 1 limits moving of the carriage 1 towards the guide rail 1 1 . The position of the carriage 1 in the third direction C is thus maintained constant.

Turning of the guide wheels 4a, 4b about the pivot axis 5 is limited to a certain angle. For instance, the guide arrangement can be configured to allow the first guide wheel 4a and the second guide wheel 4b to turn from the direction, in which the imaginary center plane D of the guide wheel 4a, 4b is parallel to the first direction A, at most 5 degrees to each direction about the pivot axis 5. By limiting the turning of the guide wheels 4a, 4b, it is ensured that the guide wheels 4a, 4b roll smoothly. The turning angle could be limited to be at most 2 degrees to each direction, or at most 1 degree to each direction.

In the embodiment of the figures, the guide arrangement further comprises a second pair of guide wheels 14. The second pair of guide wheels comprises a third guide wheel 14a and a fourth guide wheel (not shown). The third guide wheel 14a is configured to roll on the first support surface 12a of the guide rail 11 and the fourth guide wheel is configured to roll on the second support surface 12b of the guide rail 1 1 opposite to the third guide wheel 14a. The third and fourth guide wheels are thus arranged on opposite sides of the stem of the guide rail profile.

The third guide wheel 14a and the fourth guide wheel are pivotable about a pivot axis 15. In a use position of the guide arrangement, the pivot axis 15 is parallel to the second direction B. The pivot axis 15 is located in the third direction C at a distance from an imaginary center plane E of the third and fourth guide wheels.

The guide arrangement is configured to exert a force acting in the second direction B on the first and the second support surfaces 12a, 12b via the third guide wheel 14a and the fourth guide wheel. The guide wheels are thus pressed against the support surfaces 12a, 12b of the guide rail 11 .

The second pair of guide wheels 14 is positioned in the use position of the guide arrangement below the first pair of guide wheels 4.

The second pair of guide wheels 14 functions in the same way as the first pair of guide wheels 4. When the carriage 1 moves upwards, the upper ends of the third and fourth guide wheels thus turn towards the guide rail 1 1 , and when the carriage 1 moves downwards, the lower ends of the guide wheels turn towards the guide rail 1 1.

The turning angle of the second pair of guide wheels 14 is limited in a similar way as the turning angle of the first pair of guide wheels 4.

With two pairs of guide wheels, the force keeping the carriage 1 in contact with the guide rail 1 1 can be increased. However, the second pair of guide wheels is not necessary, but even one pair of guide wheels would be sufficient. The guide arrangement could be provided even with a third pair of guide wheels functioning in a similar manner as the first and second pairs of guide wheels. The guide arrangement could be comprise even further pairs of guide wheels.

In the embodiment of the figures, the guide arrangement further comprises a third limiter element 16 connected to the frame 3 and being located in the use position of the guide arrangement below the second pair of guide wheels 14, and a fourth limiter element 17 connected to the frame 3 and being located in the use position of the guide arrangement between the first limiter element 6 and the second pair of guide wheels 14. Each of the third and the fourth limiter elements 16, 17 is configured to cooperate with a guide surface 12c of the guide rail 11 to limit the movement of the guide arrangement in the third direction C towards the guide rail 11. The fourth limiter element 17 is not necessary, but the guide arrangement could comprise only three limiter elements.

The second pair of guide wheels 14 could be arranged between the first pair of guide wheels 4 and the first limiter element 6, in which case even the third limiter element would not be necessary. The guide arrangement could thus comprise two pairs of guide wheels and limiter elements below and above the guide wheels. The configuration with two pairs of guide wheels could function even with a single limiter element arranged between the pairs of guide wheels 4, 14.

In the embodiments of the figures, the limiter elements 6, 7, 16, 17 comprise limiter wheels. The limiter wheels are configured to roll along the guide surface 12c that connects the first and the second support surfaces 12a, 12b of the guide rail 1 1 . By using wheels, the friction between the limiter elements and the guide surface 12c is lower. However, the limiter elements could also be sliding elements. The limiter elements could also be integrated into a single sliding surface. The sliding surface could be arranged between the first pair and the second pair of guide wheels, or it could extend from above the first pair of guide wheels 4 to below the second pair of guide wheels 14. A longer limiter element between the two pairs of guide wheels would be suitable in particular for a guide arrangement comprising only one limiter element. The limiter elements 6, 7, 16, 17 could also be configured to cooperate with some other surface than the surface 12c connecting the first support surface 12a and the second support surface 12b of the guide rail 1 1 . For instance, the limiter elements could cooperate with the arms 13 of the T-shaped profile of the guide rail 1 1 . In the example of the figures, where bolts for attaching the guide rail 1 1 to a wall of an elevator shaft 10 protrude through the arms 13, that would not be practical, but could be used with a different type of attachment means, which would leave at least part of the surface of the arms free.

In the embodiments of the figures, the first pair of guide wheels 4 is arranged in a first wheel assembly. Two alternative configurations are shown in figures 6 and 7. The first wheel assembly comprises the first guide wheel 4a, the second guide wheel 4b, the first limiter element 6 and the second limiter element 7. The pivot axis 5 of the first pair of guide wheels 4 forms a common pivot axis of the first wheel assembly. Pivoting of the guide wheels 4a, 4b about the pivot axis 5 thus turns also the first limiter element 6 and the second limiter element 7 about the pivot axis 5.

In the embodiments of the figures, the second pair of guide wheels 14 is arranged in a second wheel assembly. The second wheel assembly comprises the third guide wheel 14a, the fourth guide wheel, the third limiter element 16 and the fourth limiter element 17. The pivot axis 15 of the second pair of guide wheels 14 forms a common pivot axis of the second wheel assembly. Pivoting of the third and fourth guide wheels about the pivot axis 15 thus turns also the third limiter element 16 and the fourth limiter element 17 about the pivot axis 15.

By arranging the guide wheels and the limiter elements in a common wheel assembly, it is easier to ensure that the guide wheels and the limiter elements are positioned with a sufficient accuracy in respect of each other. It also allow using of less strict tolerances in manufacturing of the frame 3 of the guide arrangement. However, it is not necessary that the limiter elements 6, 7, 16, 17 are arranged to pivot about the pivot axes 5, 15. The limiter elements could be rigidly attached to the frame 3.

In the embodiment of figure 7, the first wheel assembly comprises a counterweight 18. The counterweight 18 is arranged in the second direction B on an opposite side of the pivot axis 5 compared to the first guide wheel 4a and the second guide wheel 4b. The second wheel assembly can comprise a counterweight arranged in a similar manner. The counterweight 18 balances the wheel assembly and facilitates turning of the wheel assembly when the carriage 1 starts moving downwards.

When the carriage 1 is arranged on the guide rail 1 1 , the guide arrangement is positioned so that a gap is left between the guide surface 12c and at least one of the limiter elements of each wheel assembly. This allows pivoting of the wheel assembly.

According to an embodiment of the invention, the guide arrangement comprises means for adjusting the force acting on the support surfaces 12a, 12b via the guide wheels 4a, 4b, 14a. A sufficient force is needed to prevent derailing of the carriage 1 . On the other hand, the greater the force is, the more the carriage 1 resist movement in the vertical direction, which increases the force required to lift the carriage 1 . The guide arrangement can be configured to exert on the guide rail 1 1 via the guide wheels 4a, 4b, 14a a force, which is 0.5-3 times the gravitational force acting on the carriage 1 when the carriage 1 is loaded with the maximum design load of the carriage 1 . Figure 8 shows an embodiment, where the guide arrangement is provided with bolts 22, 23 for adjusting the force exerted on the guide rail via the guide wheels 4a, 4b, 14a. Tightening of a bolt 22, 23 moves the respective guide wheel towards the respective support surface 12a, 12b thus increasing the force exerted on the guide rail 1 1 .

The force that needs to be exerted via the guide wheels on the guide rail 1 1 depends on the coefficient of friction between the guide wheels 4a, 4b, 14a and the guide rail 11 . The coefficient of friction is preferably configured to be at least 0.15, more preferably at least 0.25. The friction can be affected by the selection of the material or coating of the guide wheels. The guide wheels can be made of for example polyurethan. The coefficient of friction between steel and polyurethan would be approximately 0.30. The guide wheels could also be made of a different material and coated for achieving suitable properties.

Figure 4 shows a situation, where the carriage 1 is moving upwards. The upper edges of the guide wheels 4a, 4b, 14a are turned towards the guide rail 1 1. The second limiter element 7 and the fourth limiter element 17 are in contact with the guide surface 12c. The first limiter element 6 and the third limiter element 16 are apart from the guide surface 12c. As the carriage 1 moves upwards, the guide wheels 4a, 4b, 14a steer the carriage 1 towards the guide rail 1 1 . The second and fourth limiter element 7, 17 limit the movement of the carriage 1 in the third direction C. The limiter element 7, 17 also limit turning of the guide wheels 4a, 4b, 14a. The angle between the center plane D, E of the guide wheels and the vertical direction A can be, for instance, less than 1 .0 degree. The allowed rotation angle of the guide wheels 4a, 14a depends on the initial positioning of the carriage 1 on the guide rail 1 1 .

When the moving direction of the carriage 1 changes, the rolling resistance of the guide wheels 4a, 4b, 14a resist the movement. This creates a force rotating the guide wheels 4a, 4b, 14a about the respective pivot axes 5, 15. The guide wheels 4a, 4b 14a thus turn so that the lower edges are turned towards the guide rail 1 1. The first and the third limiter elements 6, 16 come into contact with the guide surface 12c of the guide rail 1 1. The second and the fourth limiter elements 7, 17 move apart from the guide surface 12c.

Figures 10 and 1 1 show two different constructions limiting the turning angle of the guide wheels. In the embodiments of figures 10 and 1 1 , the first wheel assembly comprises a body 24. In the embodiment of figure 10, the frame 3 of the guide arrangement comprises a slot 25. The slot 25 is configured to limit movement of the body 24 of the wheel assembly, thereby limiting the turning angle of the wheel assembly about the pivot point 5. In the embodiment of figure 1 1 , the guide arrangement is provided with limiter means 26, 27 that are configured to limit the turning angle of the wheel assembly about the pivot point 5. The limiter means 26, 27 are adjustable to allow adjusting of the maximum turning angle.

The turning angle of the second wheel assembly can be limited in a similar way as the turning angle of the first wheel assembly. Even if the guide wheels are not arranged in wheel assemblies with the limiter elements, the turning of the guide wheels can be limited in a similar way.

The guide arrangement according to the invention can be used in any carriage 1 that is used for moving objects in an elevator shaft 10 along a vertical guide rail 1 1 of an elevator. In the embodiments of the figures, the carriage 1 is configured to lift guide rail elements 1 1 a for constructing a guide rail 1 1 for an elevator.

Figure 9 shows as a flowchart the method according to the invention for constructing a guide rail 1 1 for an elevator.

In a first step 101 of the method, at least one guide rail element 11 a is attached to a wall of an elevator shaft 10 at a lower end of the elevator shaft 10 to form an installed guide rail portion.

In a second step 102 of the method a carriage 1 according to the invention is arranged on the installed guide rail portion.

In a third step 103 of the method, the carriage 1 is used for lifting a guide rail element 1 1 a to an upper end of the installed guide rail portion.

In a fourth step 104 of the method the lifted guide rail element 1 1 a is attached to the wall of the elevator shaft 10 above the installed guide rail portion.

The method according to the invention allows construction of the guide rails 1 1 independently from each other. There is thus no need to construct both guide rails 1 1 of the elevator car or counterweight simultaneously. An already constructed guide rail 1 1 can thus be used for lifting objects using a carriage according to the invention, while another guide rail 1 1 is still under construction. The method according to the invention can be fully or partly automated.

It will be appreciated by a person skilled in the art that the invention is not limited to the embodiments described above, but may vary within the scope of the appended claims.