DOLLY FOR CONVEYING TROLLEYS

FIELD OF THE INVENTION

The present invention relates to a dolly for conveying trolleys particularly, although not exclusively, envisaged for use pushing shopping trolleys in car parks and the like.

BACKGROUND OF THE INVENTION It is known to collect shopping trolleys into lines and to tie the end most ones of the trolleys together. Two operators then push the trolleys about to return them to prescribed storage locations such as near the entrances to shops. A disadvantage of this of this arrangement is that two operators are needed.

It is also known to use motorised units to provide push at one end of a line of trolleys. However, such units have to be manually operated and hence two operators are still required for the collection of trolleys. That is, the prior art motorised units only deal with the problem of reducing the amount of effort required to push the trolleys, but do not deal with the issue of reducing the amount of people required for the task.

It is also known to use a dolly with means for remote control and using a reel assembly for coupling trolleys to the dolly. Such dollies however, because of their configuration, have the disadvantage that they lose traction especially when negotiating ramps and other sloping terrain and also when manoeuvring longer lines of trolleys (such as longer than about 20 trolleys) .

I have discovered that these problems can be overcome by using a remote control dolly with the drive wheels located underneath the rearmost trolleys and in operation having only these driving wheels in contract with the ground. Thus the dolly more effectively uses the force of the weight of at least some of the trolleys for increasing the traction of the drive wheels which results in significantly safer and more effective collection of trolleys.

SUMMARY OF THE INVENTION Therefore it is an object of the present invention to provide a dolly for conveying trolleys which by its

configuration and operating characteristics more effectively uses the force of the weight of at least some of the trolleys to increase the traction of the drive wheels of the dolly.

In accordance with one aspect of the present invention there is provided a dolly for conveying a line of trolleys, the line of trolleys including a rearmost trolley and a frontmost trolley, the dolly comprising: a frame for carrying the rearmost trolley whilst it is engaged with the other trolleys in the line of trolleys; and, a drive assembly attached to the frame, the drive assembly including two drive wheels and a motor, the drive wheels being able to drive the frame along the ground, and the motor being arranged to drive the drive wheels, the drive wheels maintaining traction with the ground whilst the dolly pushes the line of trolleys, the drive wheels being located under the rearmost trolley for increasing the traction of the drive wheels.

In accordance with another aspect of the present invention there is provided a gearbox of a drive assembly, the gearbox comprising: an input shaft for the input of rotary force; an output shaft for the application of rotary force to a device to be driven in forward and reverse directions; a forward gear having a radially disposed face having teeth located about it, the forward gear being secured to the input shaft for rotation with the input shaft; a reverse gear having a radially disposed face having teeth located about it, the reverse gear being journalled on the input shaft for rotation independent of the input shaft; a drive gear slidably located upon the input shaft for rotation with the input shaft, the drive gear having two radially disposed faces each with teeth located about them, the drive gear being moveable along the axis of the input shaft between a forward drive position, in which one of the faces of the drive gear engages with the face of the forward gear, and a reverse drive position, in which the other of the faces of the drive gear engages with the face of the reverse gear; and, a gear lever for selecting between engagement of the drive gear with the forward gear for causing the output shaft to

rotate in one direction and engagement of the drive gear with the reverse gear for causing the output shaft to rotate in the opposite direction.

In accordance with a further aspect of the present invention there is provided a throttle control mechanism for controlling a throttle of a motor, the throttle control mechanism having a clutch for allowing a drive motor to overrun when the throttle reaches the limit of its travel, the clutch comprising an output shaft of the motor and a belt having at least one turn around the output shaft so that when the throttle reaches the limit of its travel the output shaft can slip with respect to the belt.

Typically, the dolly has a remote control unit having a receiver operatively associated with the motor for controlling the operation of the motor for driving the drive assembly, the remote control unit being operable at a distance from the rearmost trolley so that a person operating the remote control unit can steer the line of trolleys whilst the dolly pushes the line of trolleys. The dolly of the present invention will hereinafter be described with particular reference to trolleys being shopping trolleys, although it is to be understood that it is of general applicability.

BRIEF DESCRIPTION OF THE DRAWINGS An exemplary embodiment of the present invention will now be described with reference to the accompanying drawings in which:-

Figure 1 is a perspective view, seen from above, of a dolly for conveying trolleys in accordance with the present invention, with two remote control handpieces shown in an inset;

Figure 2 is a side view of the dolly of Figure 1 shown pushing a line of 5 trolleys;

Figure 3 is perspective view, seen from above, of a platform of the dolly of Figure l;

Figure 4 is a part cut-away, part cross-section plan view of a transmission unit of the dolly of Figure 1;

Figure 5 is a perspective view, seen from above, of a throttle control mechanism of the dolly of Figure 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT (S )

In Figure 1 there is shown a dolly 10 comprising a frame 12, an engine 14, a drive assembly 16 and a remote control system including a remote control transmitter 18, a remote control receiver 20 and a throttle control mechanism 22.

The frame 12 comprises a chassis 30, a sub-frame 32, an anti-pivot bar 34, a battery carriage 36, a platform 38 and a steering arm 40.

The chassis 30 conveniently has two elongate beams 50 disposed substantially parallel to each other and extending substantially the entire length of the dolly 10. The chassis 30 acts as a support for substantially the remainder of the components of the dolly 10. Typically, the chassis is made from box section (or L-section metal materials). The sub-frame 32 is fixed below a rear end 52 of the chassis 30. The sub-frame 32 has fixed underneath it two castor type wheels 54 for enabling steering of the dolly 10 when in contact with the ground (noting that the castor wheels 54 are not in contact with the ground when the dolly 10 is pushing a line of trolleys). The sub-frame 32 also has a bar 56 disposed rearwardly of the castor wheels 54 so as to reduce the likelihood of damage to the pulley cover 90.

The anti-pivot bar 34 is located proximate a front end 56 of the chassis 30 opposite from the sub-frame 32. The anti- pivot bar 34 is used to bear against the chassis of a trolley, such as a shopping trolley, to inhibit pivoting of the dolly 10 with respect to the trolley, as described hereinafter. For this purpose the anti-pivot bar extends outwardly from the chassis 30. The battery carriage 36 is also located proximate the front end of the chassis 30. Typically, the battery carriage 36 is located below the anti-pivot bar 34. The battery carriage is designed to carry a battery 58 for use in operation of the engine 14 and the remote control receiver 20 (which typically operates at r.f. frequencies).

Also, referring to Figure 3, the platform 38 is disposed above the chassis 50 and shaped to be received underneath the rear of a shopping trolley 70 as shown in Figure 2, and especially when a plurality of the trolleys 70 are collected

together in a line of trolleys 72. For this purpose the platform 38 is conveniently trapezoidal in plan with its short edge 74 disposed forwardly and its long edge 76 disposed rearwardly. Located at the long edge 76 the platform 38 has two push brackets 78. In the present embodiment the push brackets 78 are substantially L-shaped in side elevation and are disposed upwardly and forwardly from the long edge 76. A free end 80 of each of the push brackets 78 has a hole 82 which receives a locking pin 84 for closing off a recess 86 defined between the push bracket 78 and the long edge 76. Each of the recesses 86 is dimensioned to receive the rear bar (not shown) of a rearmost trolley 88 of the line of trolleys 72. In this way the locking pins 84 lock the rearmost trolley 88 onto the platform 38. The push brackets 78 serve to be able to push the line of trolleys 72 whilst the rearmost trolley 88 is held on the platform 38. In the present embodiment the platform 38 is disposed substantially parallel to the beams 50 of the chassis 30.

It is envisaged that the platform could alternatively be in the form of a basket of a shopping trolley of the same type as those which the dolly 10 is intended to be used to collect. The platform would, in such a case, still have the same height and attitude characteristics as the platform 38 so as to provide the same operational characteristics as the platform. As shown in Figures 1 and 2 the steering arm 40 extends from the rear end 52 of the chassis 30. The steering arm 40 is disposed for enabling a user to direct or steer the dolly 10 during forward and reverse travel when not attached to the trolleys 70. When one or more of the trolleys 70 are attached to the dolly 10 steering is achieved by the operator pushing the trolleys 70 sideways.

The engine 14 is fixed onto the chassis 30 proximate the teat end 52. The engine 14 is typically an internal combustion engine although other forms of engine could be used, such as, for example, an electric motor. The engine 14 is coupled to the drive assembly 16 by a pulley housed in a pulley cover 90. Typically, the engine has a power rating of about 5.5 horse power (4 kw) in order to be able to push a line of trolleys 72 having up to about 100 in it. However, typically the dolly 10

is used to push up to about 35 to 40 trolleys 70. Longer lines of trolleys 72 require more operators to guide the line 72 intermediate of its length. I have discovered that two operators can easily manage a line of 35 to 40 trolleys 70 and the same line can be managed by one operator, although with more effect in directing the line 72. I have discovered that the configuration of the dolly 10 can propel itself almost at a jogging pace, and push a line of trolleys 72 at a fast walking pace. The drive assembly 16 comprises a transmission unit 100 and one or more, such as two drive wheels 102. The transmission unit 100 comprises a gearbox 110, a reduction box 112 and a brake assembly 114, particularly as shown in Figure 4. The gearbox 110 comprises an input shaft 120, a forward gear 122, a drive gear 124, a reverse gear 126, a planetary gear assembly 128, a casing 130, an output shaft 132, a housing 134 and a gear lever 136.

The input shaft 120 carries a cog (not shown) and is coupled to an output shaft of the engine 14 typically by two V-section drive belts for causing rotation of the input shaft 120 according to the rotation of the output shaft of the engine 14.

The forward gear 122 is fixed onto the input shaft 120 typically by a key 140 located in respective keyways in the input shaft 120 and the forward gear 122. Hence, rotation of the input shaft 120 always results in rotation of the forward gear 122.

The casing 130 is journalled upon the input shaft 120 by a bearing 146 at one of its ends and journalled to the output shaft 132 by a bearing 147 at its other end. The drive gear 124 is mounted upon the casing 130 and attached to the casing 130 for rotation with the casing 130 by a key 148. The drive gear 124 is capable of sliding axially upon the casing 130 along the length of the key 148 as indicated by arrows 150 and 152. This sliding movement allows the drive gear 124 to move between engagement with the forward gear 122 and the reverse gear 126. To achieve this sliding the drive gear 124 has a circumferential channel 158 which receives a selector 160 of

the gear lever 136. The drive gear 124 is free to rotate with respect to the selector 160. However, sideways movement of the gear lever 136 as indicated by arrows 162 and 164 moves the drive gear 124 between engagement with the forward gear 122 and the reverse gear 126 respectively.

The reverse gear 126 is actually fixed to the housing 134 of the gearbox 110 and is not capable of rotating with either the input shaft 120 or the output shaft 132. One or more screws 170 are provided for fixing the reverse gear 126 to the housing 134. The reverse gear 126 actually fixes the casing 130 to the housing 134 to prevent rotation of the casing 130 with the input shaft 120.

The planetary gear assembly 128 has an input bevelled gear 174 which is attached to an end of the input shaft 120 inside the casing 130, two intermediate bevelled gears 176 which are journalled upon an axle 177 to an inside of the casing 130, and an output bevelled gear 178 which is attached to an end of the output shaft 132. The intermediate bevelled gears 176 mesh between the input bevelled gear 174 and the output bevelled gear 178. Hence, rotation of the input bevelled gear 174 in one direction causes rotation of the output bevelled gear 178 in the opposite direction, but only when the casing 130 is stationary with respect to the housing 134. However, the input shaft 120 can only rotate with respect to the axle 177 when the casing 130 is stationary with respect to the housing 134. Then rotation of the input shaft 120 in one direction causes rotation of the output shaft 132 in the opposite direction through the planetary gear assembly 128 when the drive gear 124 is engaged with the reverse gear 126. Forward drive torque is transmitted through the gearbox 110 via a path from the input shaft 120, through the forward gear 122, through the drive gear 124, through the key 148 to the casing 130 which causes the casing 130 to rotated with respect to the housing 134. This rotation of the casing 130 causes the axle 177 to rotate with the input shaft 120 and hence the intermediate bevelled gears 176 of the planetary gear assembly 128 do not rotate. As a result the output bevelled gear 178 is locked to the input shaft 120 and hence the output shaft 132 is locked to the input shaft 120.

Reverse drive torque is transmitted through the gearbox 110 via a path from the input shaft 120, through the input bevelled gear 174 for rotating the intermediate bevelled gears 176 (since the casing 130 is fixed to the housing 134 by the engagement of the drive gear 124 with the reverse gear 126), which causes the output bevelled gear 178 to rotate in the opposite direction.

It is important to note that in the forward direction of drive the torque which can be transmitted is not limited by the torque which can be carried by the engagement of the teeth of the bevelled gears 174 to 178. This is the case since when in the forward direction the axle 177 rotates with the input shaft 120. Hence, in the forward direction the amount of torque which can be transmitted is limited only by the shear strength of the teeth of the forward gear and the drive gear, and the shear strength of the keys 140 and 148, which ever has the lesser shear strength. Also, since the forward gear 122 and the drive gear 124 are on the same axis it is possible to use a relatively large square type tooth (such as used in a dog drive) for providing a shear strength which is much larger than that which can be accommodated by conventional cog teeth (such as used in bevelled gears).

The term "reverse gear" 126 is in fact a misnomer since the reverse gear 126 does not actually transmit power from the input shaft 120 to the output shaft 132. The reverse gear 126 is referred to as such since it is conceptually the device used to set the gearbox 110 into its reverse mode of operation. It is the operation of the planetary gear 128 which achieves the reversing of the rotation of the output shaft 134. The reduction box 112 comprises a housing 190, an input shaft 192, a worm gear 194, and an output shaft in the form of an axle 196 also as shown in Figure 4.

The housing 190 has a mounting plate 200 which is used to fix the gearbox 110 onto the reduction box 112. The mounting plate 200 has a bearing 202 for journalling the input shaft 192. The housing 190 also has 4 mounting flanges 204 for mounting the reduction box 112 underneath and to the chassis 30.

The input shaft 192 is connected to the output shaft 132

of the gearbox 110 by a coupling 210. Typically, the coupling 210 has two face plates, one fixed to each of the shafts 192 and 132. The shafts 192 and 132 are then coupled together by bolting the two face plates together. The worm gear 194 typically has a reduction of about 15:1 so that the axle 196 rotates 15 times slower than the input shaft 120 of the gearbox 110.

The axle 196 extends out of each side of the housing 190. The axle 196 has one drive wheel 102 attached to each of its ends 222. The wheels 102 are typically attached to the axle 196 is conventional manner. The diameter of the drive wheels 102 in relation to the castor wheels 54 is such that the platform 38 is angled upwardly at the front end 56 of the chassis 30 when the castor wheels 54 are in contact with the ground. That is, when the dolly 10 is not carrying any trolleys 70 the platform 38 is angled upwardly. Then when a line of trolleys 72 is attached to the dolly 10 the castor wheels 54 lift of the ground by an amount A as shown in Figure 2. The clearance A of the castor wheels 54 is important to reduce the likelihood of the castor wheels touching the ground during pushing of the line of trolleys 72. The result of the castor wheels 54 touching the ground in such circumstances is that one or both of the drive wheels 102 loose traction with the ground and the dolly 10 is less able to push the line of trolleys 72. The clearance A must be large enough to avoid contact with humps in the road and car parks- used to control the speed of traffic (known as speed humps) and to avoid contact with the ground when the ground changes angle such as when going up a ramp or the like. In the present embodiment the clearance A is about 120 mm.

The wheels 102 are also of such a diameter that the rear castor wheels 240 of the rearmost trolley 88 and its next adjacent few trolleys 70 are lifted off the ground. In the embodiment shown in Figure 2 the drive wheels 102 have a diameter which causes the rear castor wheels 240 of the three rearmost trolleys 70 to be lifted off the ground. This lifting increase the load on the drive wheels 102 and gives them more traction, which enables the dolly 10 to push more trolleys 70 than would otherwise be the case.

It is envisaged that a single drive wheel 102 could be used provided that it is wide, such as in the case of a roller. The brake assembly 114 comprises a brake drum 241, a brake lining 241a, a hydraulic pump 242, and an electrical ram 242a. The brake drum 241 is attached to the coupling 210 and disposed inside and coaxial with the brake lining 241a. The brake lining 241a is driven by the hydraulic pump 242 for forcing the brake lining 241a into contact with the brake drum 241 for effecting a braking action on the output shaft 132. The electrical ram 242a is connected by wires 243 to the remote control receiver 20 which is configured to allow control of the ram 242a by operation of control button 3 of the remote control transmitter 18 (see Figure 1) as described hereinafter.

Also, the electrical ram 242a could be controlled by a transistorised tilt switch so that when the dolly 10 goes down a slope the brake assembly 114 activated enough to control the rate of decent of the dolly 10 and its line of trolleys 72. In this way the dolly 10 and the line of trolleys 72 is inhibited from gaining speed when travelling down a slope. Also, the brake assembly 114 can be used as a parking brake when the line of trolleys 72 is required to be held stationary on a slope, such as, for example, in a sloping car park.

The anti-pivot bar 34 is disposed to bear against the two sides of a chassis 244 of the rearmost trolley 88 for inhibiting pivoting of the dolly 10, about a horizontal axis through the wheels 102, with respect to the rearmost trolley 88. This assists in keeping the rearmost few trolleys 70 together and hence to keep the force of the weight of the rearmost few trolleys 70 over the wheels 102. Also, and most importantly, the anti-pivot bar 34 serves to convert the reactive torque experienced by the trolley 88 from the dolly 10 into a force applied vertically downwardly through the drive wheels 102 - thus further increasing the traction of the drive wheels 102. Hence, the anti-pivot bar 34 causes the traction of the drive wheels 102 to increase as the force required to push the line of trolleys 72 increases.

As shown in Figure 5 the throttle control mechanism 22 has a DC motor 250, an endless belt 252 and a pulley 254.

The DC motor 250 is electrically connected to the battery

58 and to the remote control receiver 20 so that the operation of the motor 250 is controlled by signal sent from the remote control transmitter 18. The DC motor 250 has an output shaft 260 which receives a plurality of turns 262 of the endless belt 252, such as 2 turns of the endless belt 252. The turns 262 of the endless belt 252 and the output shaft 260 serve to function as an overrun clutch 264. The purpose of the overrun clutch 264 is to allow the output shaft 260 to slip with respect to the endless belt 252 in the event that the endless belt 252 is inhibited from further movement.

The endless belt 252 also has a plurality of turns 266 about a throttle shaft 268 of the engine 14. Movement of the endless belt 252 causes translation of the throttle shaft 268 in the direction of arrows 270 and 272. The throttle shaft 268 is fixed to one end of the throttle lever 280 which is able to pivot about a pivot 282. Hence, the throttle shaft 268 can be moved either by operation of the motor 250 or by hand control of the throttle lever 280.

As shown in Figure 1, the remote control transmitter 18 has 4 control buttons 290 labelled 1, 2, 3 and 4. The control button 1 is configured for causing the motor 250 to rotate its output shaft 260 in one direction for moving the throttle shaft 268 for increasing the revolutions of the engine 14. The control button 2 is configured for causing the motor 250 to rotate its output shaft 260 in the other direction for moving the throttle shaft 268 for reducing the revolutions of the engine 14 to idle speed. The control button 3 is configured for use as an emergency brake control function for electrically activating a mechanical brake (not shown) located within the gearbox 110 on the output shaft 132 for bringing the dolly 10 to a stop. The control button 4 is configured for use reducing the throttle to idle speed and then turn the engine 14 off (referred to as a "kill" switch).

In Figure 1 there is also shown an emergency kill switch 292 whose operation is similar to that of the control button 4 of the remote control transmitter 18. The emergency kill switch 292 is intended to be worn around the neck of the operator of the dolly 10 for enabling the operator to stop the dolly 10 in the case of an emergency. The emergency kill

switch 292 sends an r.f. signal to a second remote control receiver circuit, identical to the above mentioned remote control receiver unit 20, so that in the event of failure of the remote control receiver unit 20 the dolly 10 can still be stopped.

Preferably, the remote control circuitry of the remote control receiver 20 is designed so that the dolly 10 will be brought to a stop in the event of any failure of the control systems. Such failure may include battery failure in the remote control transmitter 18, wire breakage in the remote control receiver 20 or the like.

In use, the engine 14 is started in conventional manner. The steering arm 40 is used to position the dolly 10 behind a trolley 70 to be pushed. At this time there are no trolleys 70 on the platform 38 and so the castor wheels 54 are in contact with the ground. The steering arm 40 is then lifted upward to lift the castor wheels 54 off the ground, and a trolley 70 as pulled onto the platform 38. Alternatively, the trolley 70 may be lifted onto the platform 38. The rear bar of the trolley 70 is located in the recess 86 of the push brackets 78 and the locking pins 84 are lowered through the holes 82 to close off the recesses 86 and thereby lock the trolley 70 onto the platform 38. The trolley 70 so secured becomes the rearmost trolley 88. The control button 1 of the remote control transmitter 18 is then pressed continuously to cause the remote control receiver 20 to allow power to flow to the DC motor 250 which cause the output shaft 260 to rotate which causes the throttle shaft 268 to move and hence the engine revs up. The power of the engine 14 is applied by the V-belt to the input shaft 120 of the gearbox 110.

With the gear lever 136 in the forward position (labelled F in Figure 4 and indicated by arrow 162) the power of the engine is transmitted from the input shaft 120 to the forward gear 122 via the key 140, from the forward gear 122 to the casing 130 via the key 148 which causes the casing 130 to rotate with the input shaft 120. This rotation causes the axle 177 carrying the intermediate bevelled gears 176 of the planetary gear assembly 128 which results in a locking of the

output bevelled gear 178 to the input bevelled gear 174. Hence, the output shaft 132 rotates with the input shaft 120. The rotation of the output shaft 132 causes rotation of the axle 196 of the reduction box 112, although at a reduced rate - such as a 15:1 reduction. The drive wheels 102 are thus caused to rotate and the dolly 10 travels in a forward direction.

The reduction box 112 amplifies the torque of the engine 14 and in the present embodiment is able to push 30 trolleys 70 is a line. The construction of the gearbox 110 is important so as to provide a gearbox which can transmit a large torque whilst being small and relatively light weight.

When another trolley 70 is reached the operator presses the control button 2 to cause the throttle shaft to be moved in the other direction for reducing the revs of the engine and thus slowing the speed of the dolly 10 to a stop. The engine 14 has a centrifugal clutch driving the input shaft 120 of the gearbox 110, so that once the revs of the engine 14 reduce below a predetermined level the drive to the input shaft 120 is removed and the dolly 10 will no longer be driven in a forward direction. The trolley 70 is then pushed onto the trolleys 70 which are already in the line of trolleys 72. Typically, the trolleys 70 are held together by using a rope maintained in a reel. The reel allows the rope to be payed out and reeled in as required. Also, it is helpful to use two such devices: one to keep the first few trolleys 70 together; and the other to hold the rest of the trolleys 70 in the line of trolleys 72. This is desirable since otherwise the first few trolleys 70 tend to separate and break out of the line of trolleys 72 when negotiating corners. Once the new trolley 70 has been attached to the line of trolleys 72 the rope is used to hold it in place. The gear lever 136 is then set to the forward position F for pushing the line of trolleys 72.

When it is desired to pull the line of trolleys 72 backwardly, such, as out of a trolley storage bay, the gear lever 136 is set to the reverse position R for driving the dolly 10 backwards.

The dolly 10 of the present invention has the advantage that it has its drive wheels 102 under the load of the trolleys

70 are hence has greater traction and hence pushing power than would otherwise be the case. Also, since the rearmost few trolleys 70 have their rear castor wheels 240 lifted off the ground the amount of the traction is further increased. Further, by the action of the anti-pivot bar the amount of traction of the drive wheels 102 increase with the amount of force required to push the line of trolleys 72. Further, since the castor wheels 54 of the dolly 10 are inhibited from coming into contact with the ground during pushing of the line of trolleys 72 the chances of loosing traction of the drive wheels 102 is greatly reduced. That is, the dolly 10 is more reliable in the task of pushing the trolleys. Further, since the position of the engine 14 throttle lever 280 can be controlled remotely, and the trolleys 70 in the line of trolleys 72 can be held together, it is relatively easy for one person to operate the dolly 10 and collect the trolleys 70.

The gearbox 110 of the present invention has the advantage that the amount of torque which it can transmit when in the forward mode is not limited by the torque which can be transmitted by the engagement of the teeth of gears, but limited only by the torque which can be transmitted by a plurality of dog teeth of the forward gear 122 (each of the dog teeth extending over about 15° of arc around the forward gear 122). Hence, the gearbox 110 is able to transmit large torques in the forward mode, whilst being small and relatively light weight.

The throttle control mechanism 22 of the present invention has the advantage that it has an overrun clutch 264 which is simple, yet robust.

It is envisage that a mechanical brake be arranged on the output shaft 132 of the gearbox 110. The brake could be operated by an electrical solenoid controlled by a tilt switch. Hence, the mechanical brake could be made to be applied lightly to slow the maximum speed of the dolly 10 in the event that it goes down hill. The tilt switch could be a transistor tilt switch, which is much more accurate that the conventional mercury tilt switches. The brake could also be controlled to apply fully in emergency situations and when the dolly 10 is

stationary so as to act as a parking brake.

Modifications and variations such as would be apparent to a skill addressee are considered within the scope of the present invention. For example, other forms of engine could be used, such as, for example, battery driven motor or the like.