WO1994021505A1

WO1994021505A1 - Trolley

Info

Publication number: WO1994021505A1
Application number: PCT/SE1994/000249
Authority: WO
Inventors: Boh Westerlund
Original assignee: Boh Westerlund
Priority date: 1993-03-23
Filing date: 1994-03-22
Publication date: 1994-09-29
Also published as: SE9300951L; FI954519A0; DK104395A; FI954519A; AU6389294A; CA2158158A1; NO953743D0; EP0689513A1; SE501116C2; SE9300951D0; NO953743L

Abstract

The invention relates to a manually activatable, wheel-supported trolley which can be moved on an underlying supportive surface and which includes a load-receiving surface or implement which is supported at its corner-related region by supportive devices (casters), and which includes two centrally positioned wheels for engagement with the underlying surface and that the centrally positioned wheels (15, 16) are driven individually and electrically; in that the trolley includes an arrangement (2) whose positional setting determines the direction in which the trolley is driven and which is adapted to activate one or more functions in accordance with the positional setting of a first device (21) in relation to a second device (22); and in that the electrically-driven wheels (15, 16) are edge-related.

Description

TITLE OF INVENTION: TROLLEY

TECHNICAL FIELD

The present invention relates to a manually-activated trolley which can be moved along a trolley-supporting surface on wheels and which includes one or more load- receiving surfaces or an implement supported in its corner-related regions by support devices (casters), and two centrally positioned wheels which can be caused to abut a supporting surface.

In order to operate the trolley, the trolley requires access to an arrangement which is able to influence a number of functions in accordance with the positional setting of a first device relative to a second (fixed) device.

BACKGROUND ART

There are several earlier known examples of arrange¬ ments which are able to influence one or both of two (or more) different functions in accordance with the positional setting of a first device in relation to a second (fixed) device, and which includes means for will enable the first device to be moved in relation to the second device.

Reference is made in this respect to the prior art disclosed in the International Patent Application PCT/SE89/00365.

This publication also discloses a manually-activated trolley or like device which can be moved on wheels over a supporting surface and which includes a load- receiving surface which is supported at its corner- related region by support devices or support wheels, and with which the direction in which two corner- related wheels are dtiven will depend on the positional setting of an arrangement which is adapted to activate one or more functions in accordance with the positional setting of a first device in relation to a second device.

Similar to the present invention, the trolley des¬ cribed in this patent publication includes a battery- accommodating space, control equipment by means of which the driven wheels can be turned in a chosen direction and at a chosen speed or at a chosen torque, and the requisite devices for operating the control equipment.

With regard to the proposed usage of the present invention, it can also be mentioned that also known to the art are solely hand-manoeuvered transportation trolleys that can be used in departmental stores and shopping facilities and which include two fixed edge- orientated wheels which are positioned within the central region of the load-receiving surface, and which casters positioned at the four corner-related regions of said surface. The two fixed wheels are intended primarily to support the load and the for- wardly located or the rearwardly located pairs of casters serve as supports, depending on which side of the two fixed wheels the centre of gravity is situat¬ ed. Experiences with this type of trolley show that while the trolleys are difficult to manoeuver, manoeu- verability becomes easier when the centre of gravity is located close to the fixed wheels or actually within the wheels themselves. Such trolleys are re¬ ferred to as "hand-picking trolleys" and are used for loads of up to 100-200 kg.

It is also knowr to use trolleys which include a centrally placec electrically-driven wheel, for for¬ ward or rearward transportation at a low speed and with a relatively small load, less than 100 kg. These trolleys are called library trolleys because of their special use.

It is known to use two centrally positioned drive motors with individual control and to support the load-receiving surface on air springs, particularly in the case of heavy loads. The drive motors used are most often air-driven motors.

It is also known to propel wheelchairs and the like with the aid of two edge-related, separately and electrically driven wheels, where the requisite con¬ trol equipment can be controlled by a manoeuvering arm, a so-called joy stick.

In this case, the control equipment is adapted so that if the manoeuvering arm is moved forwards, the wheel¬ chair will be driven in a forward direction, and vice- versa. If the manoeuvering or steering arm is moved to one side, the wheels will be driven so as to turn the wheelchair around a point located centrally between the drive wheels.

Such a manoeuvering arrangement is constructed so that a minimum of force is required to move the steering arm and the manoeuvering arrangement is placed within the forward part of the wheelchair, and at least forwardly of the driven wheels.

The present invention is intended to provide a trolley or an implement in which the load-receiving surface is dimensioned for loads of up to 400 kg, and which includes a battery space and the control equipment necessary for operating the two drive wheels.

The concept of -_.ae invention is a development of the construction known as a "hand-picking trolley". Considering the features related to the present invention the following prior art embodiments do show constructions related to other technical fields than that of the present invention.

Thus US-A-3,225,853 is disclosing a Control Handle for Golf Carts.

US-A-3,896,892 is disclosing a Manual Control for a Self-propelled Vehicle and

US-A-4,646,862 is disclosing a Floor Cleaning Ma¬ chine.

The publication US-A-4,475,611 is disclosing a Scaffold Propulsion Unit resting on four caster means 18 and is driven by a scaffold propulsion unit 30.

The floating action of the wheeled frame member 37 is advan¬ tageous in that the downward force on the drive wheels 47 and 50 is functioning solely of the weight of the frame member 37 and the batteries thereon and is independent of the weight of the scaffold and the load thereon. As a consequence, the load capacity is limited by the frictional traction obtainable with the constant weight on the drive wheels. In turn, this will add in preventing the scaffold from being power driven, when it is improperly overloaded.

The floating action of the wheeled frame member is also advantageous in that the wheels 47 and 50 can be driven over relatively thin obstacles, such as boards or the like, wit- hout causing the scaffold to tilt. The independent vertical movement of the wheeled frame member 37 relative to the scaf¬ fold and a first and a second frame members makes it easy to provide switch 43 to shut off power to the motors in the event of a predetermined amount of such relative movement so that the drive whe Is will be prevented from being driven over an undesirably thick obstacle. SUMMARY OF THE INVENTION

TECHNICAL PROBLEMS

When considering the present standpoint of techniques as described above, it will be seen that a technical problem resides in the ability to provide an electri¬ cally-driven trolley which has a unique control ar¬ rangement in combination with unique orientation of two centrally placed and side-related drive motors with associated driving wheels, where each drive motor can be separately controlled, and therewith to provide a trolley construction which can be readily manoeu- vered by a driver walking on the trolley-supporting surface with the aid of a well-balanced control sys¬ tem, irrespective of the load carried by the trolley.

In this regard, a technical problem resides in realiz¬ ing the significance of creating in a "hand-picking trolley" or an implement conditions with which the control arrangement with requisite manoeuvering ar¬ rangement and the positioning of the driven wheels will enable the trolley to be propelled easily and smoothly in all directions irrespective of the load carried thereon by a driver walking on the supporting surface, or in some instances by a driver riding on the trolley, and in which the trolley can be propelled freely in all directions without the assistance of the electrical drive system, or with only slight assist- ance from the electrical drive system, when the trol¬ ley is propelled with no load.

Another technical problem resides in realizing that an effective, adapted torque is required when turning the trolley and that manoeuvering of a loaded trolley is facilitated wher. the common centre of the drive wheels is placed as close as possible to the gravitational centre point of the load, while the drive wheels are placed as far as possible from the centre and on opposite sides of the centre of gravity.

A further technical problem is one of realizing that there is required a stabilizing function which will drive the two motors in the same direction and at the same speed when the control handle is activated in a forward/rearward direction.

Another technical problem is one of realizing the necessity of a horizontally directed side-movement of a steering handle to obtain conformity in the movement pattern when the drive wheels are spaced forwardly of the handle.

It will be seen that another technical problem is one of realizing the necessity of a servo function for propelling smoothly an electrically-driven trolley which is equipped with mutually spaced twin drive- motors.

Another technical problem is one of realizing that when an implement control system, for instance a trolley control system, is intended to be activated by a person walking on a trolley-supporting surface

(floor) and steering the implement, there is required for smoothness of operation a balanced and sprung servo function which is so constructed that said person must first manually initiate direction, where- after the implement is moved in the direction initiat¬ ed with the aid of its drive-motors.

Another technical problem is one of realizing that when the control system of an implement, for instance a trolley, is intended to be activated by a person steering the ift^lement and walking on a supporting surface (floor), there is required for smoothness of operation the manual application of forces which, after having initiated direction, are able to produce control signals which will cause the trolley to move at a desired speed, whereafter the control system activates the implement for movement at the speed of the person in control of the trolley through the medium of its drive motors.

Another technical problem resides in realizing the necessity of a counter-suspension in the control system which is so high that the trolley, in the absence of a drive function, can be moved carefully on a flat supporting surface solely by manual force.

It will that a further technical problem is one of realizing that the specific counter-suspension in the control system must be constructed so as not to be excessively high but to obtain a driver-ergonomically acceptable load, i.e. a load of normally between 10-15 N.

It will also be seen that a technical problem is one of realizing that when propelling the trolley at a high speed or over a long distance or when the driver is seated on the trolley, the force applied to the control system must be relieved, which can be effected by means of a rod (31) coupled to the trolley immedi¬ ately in front of the control handle.

Another technical problem is one of realizing that for safe handling of a motor-driven vehicle of this kind, the vehicle should include a safety function which will ensure that the trolley/implement can only be propelled when the handle is gripped by a human hand, and that the vehicle will stop when the control handle is released.

Another technical problem resides in realizing the significance of providing such conditions in the for¬ ward/rearward direction, and particularly in each side direction, that when steering via said arrangement, a steering direction initiated by displacing a manoeu¬ vering handle will cause the (rear) part of the trol¬ ley where the steering or control arrangement is located to move in the same direction.

It will also be seen that a technical problem resides in realizing the significance of incorporating part of the steering or control arrangement in a horizontally positioned handle which when moved will initiate the requisite steering of the trolley and which can be gripped with both hands for improved trolley control.

It will also be seen that a technical problem resides in realizing the significance of enabling two corner- related wheels to be lowered to an extent such that the two driven wheels will be free from abutment with the supporting surface, or by enabling the two driven wheels to be lifted up.

When considering the present standpoint of techniques with regard to an arrangement for activating one or two of two or more functions in accordance with the positional setting of a first device in relation to a second device, and with means for enabling the first device to be moved in relation to the second device, it will be seen that a technical problem resides in realizing the significance of providing conditions in one use application of a movable trolley which will enable one of said functions to be activated upon relative movement in one direction and the other of said functions to be activated upon relative movement in a direction which is at right angles or generally at right angles to said direction.

It will also be seen that a technical problem resides in realizing the significance of providing the second device in the form of a horizontally extending rail, rod or the like, and for the first device to have a cross-sectional shape which fully or partially sur¬ rounds the second device.

It will also be seen that a technical problem resides in realizing that one or two of said functions shall be initiated upon relative axial displacement between the devices, and that one or two others of said func¬ tions shall be initiated in response to relative radial displacement between the devices.

It will also be seen that a technical problem is one of realizing the significance of utilizing for each of said functions a potentiometer which coactε with the second of said devices and which can be activated progressively in response to relative movement of the first device.

It will also be realized, particularly with regard to application of a manually movable trolley, that a technical problem resides in realizing the signifi¬ cance of allowing one of said functions to be comprise common activation of two electrically-driven wheels, and the other of said functions to be comprise driving of said wheels in an opposite direction.

SOLUTION

With the intention of solving one or more of the aforesaid technical problems, the present invention takes as its starting point a trolley which can be moved manually along a supporting surface on wheels and which has a load-receiving surface or an implement supported at its corner-related regions by support devices (casters) and centrally positioned wheels which are intended to engage the trolley-supporting surface.

It is proposed in accordance with the invention that the centrally positioned wheels are electrically driven and that the drive direction is dependent on the positional setting of an arrangement which func¬ tions to activate one or more functions in accordance with the positional setting of a first device in relation to a second device. The electrically-driven wheels are two in number and are positioned within the central region of the load-receiving surface and are edge-related and separately drivable through the medium of said control arrangement.

It is also proposed that the two driven wheels are positioned beneath, or essentially beneath, the centre of gravity of a loaded trolley.

The two drive wheels are arranged to support the trolley on the supporting surface such that at least two corner-related support devices are located slight¬ ly above said supporting surface.

Two corner-related devices, or wheels, can be lowered to an extent such that the two driven wheels can be lifted free from their engagement with the supporting surface, or alternatively the driven wheels may be constructed so as to enable them to be lifted or retracted.

According to the invention with regard to the arrange¬ ment for activating one or two functions from among a number of functions in response to the positional setting of a first device in relation to a second device and provided with means for causing the first device to move in relation to the second device, one of said functions will be initiated in response to relative displacement in one direction and a second of said functions shall be initiated in response to relative displacement in a direction which is at right angles or generally at right angles to said direction. According to other proposed embodiments, the second device has the form of a horizontal rail, rod or the like, and the first device has a cross-sectional shape which completely or partially surrounds the second device.

Furthermore, it is proposed that one of said functions will be activated by a generally horizontal axial movement between the devices and that a second of said functions will be activated through radial displace¬ ment between the devices.

According to one embodiment of the invention, poten¬ tiometers are arranged to coact with the second of said devices and are capable of being activated pro¬ gressively in response to the relative movement of the first device.

One of said functions comprise common activation of two electrically-driven wheels and the other of said functions is comprised of opposite driving of said wheels.

ADVANTAGES

Those advantages primarily afforded by an inventive trolley which utilizes a control arrangement to initi¬ ate one or two of several functions in response to the positional setting of a first device in relation to a second device reside in the provision of conditions which enable the trolley to be manoeuvered easily with the aid of two driven wheels that are positioned within the central region of the load-receiving sur¬ face and edge-related and orientated so that said wheels are located in or essentially beneath the centre of gravity of a loaded trolley. The primary characteristic features of a trolley constructed in accordance with the present invention are set forth in the characterizing clause of the following Claim 1.

BRIEF DESCRIPTION OF THE DRAWINGS

An exemplifying embodiment of an arrangement fitted to and coacting with an inventive trolley at present preferred will now be described in more detail with reference to the accompanying drawings, in which

Figure 1 illustrates schematically and in side view a trolley equipped with an inventive arrange¬ ment;

Figure 2 is a view from beneath of a load-receiving surface of the trolley;

Figure 3 illustrates the arrangement for activating one or both of two functions in accordance with the positional setting of a first de¬ vice in relation to a second device, in different positional settings A, B, C and D;

Figure 4 is a simplified circuit diagram for driving with the aid of potentiometers or rheostats two electrically-driven wheels resting on a supporting surface; and

Figure 5 illustrates the arrangement shown in Figure 3 in two different sectional views.

DESCRIPTION OF EMBODIMENTS AT PRESENT PREFERRED

Figure 1 is a side view of a trolley 1 constructed in accordance with the invention and including an arrangement 2 which is comprised of a first device 21 and second device 22 and which is intended to initiate of one or both of two mirror-image functions in accor¬ dance with the positional setting of a first device 21 in relation to said second device 22, and means for causing the first device 21 to move relative to the second device 22.

This will be described in more detail with reference to Figure 3 and Figure 5.

Although not shown in Figure 1, the trolley is intend¬ ed to be operated manually for movement along a trol¬ ley-supporting surface 3 with the aid of support devices, such as casters and/or driven wheels.

The trolley 1 includes a load-receiving surface 10 which is supported at its corner-related regions by four supportive devices in the form of casters, front caster-pairs 11, 12 and rear caster-pairs 13, 14, which are fitted to the underside of the load-receiv¬ ing surface 10 in a known manner.

The illustrated trolley also includes electrically- driven wheels 15, 16 which engage the trolley-support¬ ing surface 3. The direction in which the wheels swivel and/or the direction in which the wheels are driven will depend on the positional setting of the arrangement 2, which is constructed to initiate sever- al functions in accordance with the positional setting of the first device 21 in relation to said second device 22.

The electrically-driven wheels 15, 16 are two in number and are positioned within the central region of the load-receiving surface 10 in the vicinity of its edges. The trolley also includes a space la for the accommo¬ dation of batteries and the requisite control equip¬ ment for controlling the direction, speed and torque of the electrically-driven wheels 15 and 16 in re¬ sponse to the positional setting of the arrangement 2.

The distance denoted by the reference "a" is intended to illustrate the area within which the wheels 15, 16 will normally be mounted.

It is particularly preferred in accordance with the invention that the two driven wheels will be located beneath, or essentially beneath, the centre of gravity of a loaded trolley 1.

The two driven wheels 15, 16 are arranged to bear against the supporting surface 3 so that at least two corner-related support devices, the pair of casters 13, 14, will be spaced slightly above the supporting surface.

The pair of casters 11, 12 may, of course, also be spaced above the supporting surface 3, depending on the position of the centre of gravity.

It is also conceivable to allow the two corner-related devices or caster-pairs 13, 14 to be raised and low¬ ered with the aid of manually or electrically operated lifting and lowering devices (not shown) to an extent such that the two driven wheels 15, 16 will be free from engagement with the supporting surface 3.

It is also conceivable to provide the driven wheels 15 and 16 with means which will enable them to be raised and lowered.

During this function, the drive system is disengaged and the trolley is manoeuvered fully manually. An arrangement by means of which one or two of several functions can be initiated in response to the posi¬ tional setting of the first device 21 in relation to the second device 22 of the control arrangement 2 will now be described with reference to Figures 3 and 5, while means for causing the first device to move in relation to the second device will be described with reference to Figure 4.

One of the aforesaid functions or facilities comprises common driving of the wheels 15, 16 in mutually the same direction, while the other function involves driving of the wheels 15, 16 in the opposite direc¬ tion. These two functions can be effected in two directions of rotation.

One of the aforesaid functions is initiated by rela¬ tive movement of said devices in one direction and the other of said functions is activated by relative movement of said device in a direction which is at right angles or essentially at right angles to the first-mentioned direction.

Combined movement, or displacement, will cause the two functions to be initiated simultaneously and to a greater or lesser extent.

The device 21 is connected to the device 22 with the aid of a spring device 23, 24. As a result, the de- vices 21 and 22 will occupy the position shown at "A" when at rest.

Two potentiometers 41, 42 are fixed in relation to the second device 22 and are influenced successively by the relative movement generated by the first device 21.

In the position "B" , the first device 21 has been moved to the left causing the potentiometer 41 to be influenced to the left, wherewith the left wheel 16 drives in a forward direction and the right wheel 15 drives in a rearward direction, thereby causing the trolley to swing to the right.

The position "C" illustrates that the end-region 21a is in a neutral position, whereas the end-region 21b has been moved forwards to a maximum and into abutment with the second device 22 and therewith drives the wheels 15, 16 at half speed, since the potentiometer 42 is only partially used.

In position "D" , on the other hand, the first device 21 has been moved to a fully forwards position and the potentiometer 42 is fully used and the wheels 15, 16 therewith drives the trolley forwards.

Figure 4 is a circuit diagram illustrating the poten¬ tiometers 41 and 42 and showing how a detection cir- cuit or unit 43 coacts with the first device 21 in a manner to increase the positive voltage in dependence on displacement of the potentiometer contact to the left, via a device 44, and to drive the left wheel 16 for forward drive, and to successively increase the negative voltage to the right wheel 15 to the same extent.

Similarly, when the potentiometer contact is moved to the right, the supply voltage is increased successive- ly via a device 45, although in an opposite direction.

It can be mentioned that with the aid of a detection circuit or unit 46, the negative potential for both right and left wheels 15, 16 will be increased succes- sively via the device 47 when the potentiometer con¬ tact of the potentiometer 42 is moved downwards in Figure 4. 1 T

When the potentiometer contact is moved upwards, the unit 46 will apply a successively increasing positive voltage to both wheels 16, 15, via the device 48, so as to move the trolley in a forwards direction.

The trolley 1 can be easily manoeuvered with the aid of a well-balanced servo system which is constructed so that both drive motors to the wheels 15, 16 can be activated for travel in a forward/rearward direction by a spring-mounted handle 2.

When the handle 21 is moved forwards, the drive motors are activated to drive the trolley in a forward direc¬ tion, while when the handle is drawn backwards, the motors are activated to drive the trolley on reverse. If the handle 21 is moved to one side, the motors cause the trolley 1 to swing. If the handle is moved to the left, the motors cause the rear part, where the handle is fixed, of the trolley to swing to the left and the trolley will therewith follow the directional sense implied by the manually applied force.

It will be understood from the aforegoing that when the handle 21 is moved obliquely forwards, the trolley will swing or turn while moving forwards at the same time.

Movement of the trolley is thus initiated by means of the control handle. When the driver remains in place on the trolley-supporting surface, the trolley will move in accordance with the new position of the driv¬ er's hand/hands and then stop. If the driver moves, the trolley will "chase its handle" in order to take a rest position.

A particular characteristic of this system is that the control system is comprised of a control handle 21 which can be gripped by one or both hands of the driver and which is so counter-sprung 23 as to enable an unladen trolley to be moved slowly and carefully by manual activation of the control handle, without the drive system being engaged and without the control handle moving or bottoming against its spring connec- tion, meaning that the force taken to initiate move¬ ment of the trolley is balanced at a value of beneath about 15 N.

When the drive system is engaged, the control system is able to move the trolley under its own power so that after moving the control handle the trolley is able to adopt a new position which strives towards neutralizing the applied movement of the handle.

The servo control handle 21 can be gripped with two hands therewith providing greater control over forward movement of the trolley/implement because less force is required by respective hands to change the direc¬ tion of trolley movement or the speed of the trolley and because small manoeuvering errors by one hand are compensated by the other.

The handle 21 may advantageously incorporate a facili¬ ty which activates the control system only when the handle is gripped by the driver's hand and with which the system is disengaged immediately the handle is released.

There is thus provided a servo system with which a standing person/a person walking on the floor 3 beside the trolley is able to control the trolley by means of the trolley handle and through the force of his/her hand, wherein the spring movement of the handle in¬ fluences the drive motors or the wheels proportionally to the force applied to the handle and the direction in which said force is applied.

As illustrated in Figure 3, the potentiometers 41, 42 are activated b a control system which is placed centrally in the handle. This means that movement of the handle laterally will always influence the drive system to an equal extent, whereas activation of the handle in a forwards/rearwards direction is controlled by how the hands are placed on the handle.

When the trolley is steered forwards or backwards with only one hand placed on the outer edge of the handle, the trolley can be given half power in accordance with position "C" in Figure 3.

If both hands are placed on the control handle and the trolley driven forwards, the potentiometer can be given full effect. This will result in more powerful activation of the drive motors/wheels. If the handle is gripped in its centre region, for instance with one hand, the motors can be activated to full power, although in this case there is required twice the force as that required when the motors are activated with both hands separately. In this position, however, the activating force generated by the hand is ampli¬ fied by utilizing a grip formed above a fixed rod 31.

This handle construction thus forms a balance system in the servo system necessary for handling the trolley in a smooth and efficient manner.

It is to be noted that the used expression that the two driven wheels 15, 16, are adapted to support against the trolley-supporting surface such that at least two corner- related support wheels 13, 14 will be located above the trolley-supporting surface 3 does also include that these wheels are resting towards the surface 3.

Each wheel 13, 14 can be spring-biased towards the surface and can thus be moved from an upper full load-supporting position to a lower, a surface abutting, position.

In this embodiment an upper load-supporting position of at least two corner-related support wheels will be located above the trolley-supporting surface 3 although the wheels may rest, with a small force, upon said surface.

It will also be possible to press the wheels 13, 14 towards the surface and lock them in that extended position, while the wheels 15, 16 are arranged over the surface 3.

This possibility causes a reduction in the tilting ability.

The used reostate or potentiometer can be replaced by other means, for evaluating the relative movement between the means 21 and 22. Such means can be Hall-units or the like.

Rubber spring devices can also be used in stead of the shown mechanical spring devices.

The means 21 kan be moved by one hand only in the shown two different directions.

It will be understood that the invention is not re¬ stricted to the aforedescribed and illustrated exem¬ plifying embodiment thereof and that modifications can be made within the scope of the invention as defined in the following Claims.

Claims

1. A anually operable trolley comprising a load- receiving surface, support wheels which are mounted in the corner regions of the load-receiving surface, two centrally positioned and electrically-driven wheels (15, 16), each of which is driven separately from the other and which are engagable with an underlying trolley-supporting surface ( 3), a handle assembly (2) comprising a first device (21) and a second device

(22) and operative in initiating one or more trolley functions in response to the positional setting of the first device (21) in relation to the second device (22), said electrically-driven wheels (15, 16) being mounted at respective edges of the load-receiving surface, characterized in that the two driven wheels (15, 16) are adapted to support against the trolley- supporting surface such that at least two corner- related support wheels (13, 14) will be located above the trolley-supporting surface (3) or rest slightly towards the surface (3) .

2. A trolley according to Claim 1, characterized in that the two driven wheels are located beneath or essentially beneath the centre of gravity of a loaded trolley.

3. A trolley according to Claim 1, characterized in that the two corner-related support wheels (13, 14) can be lowered to an extent such that the two driven wheels (15, 16) will move free from engagement with the trolley-supporting surface (3), or alternatively that the driven wheels (15, 16) can be raised and lowered.

4. A trolley according to Claim 1, characterized by a spring means which functions to urge the two corner- related support wheels against the trolley-supporting surface such as to stabilize the trolley.

5. An arrangement for use with a trolley according to Claims 1-4 where one function is initiated in response to relative movement of a first device (21) in a first direction relative to a second device (22), and a second function is initiated in response to relative movement of said device in a direction which is at right angles to or essentially at right angles to said first direction, characterized in that said second device (22) has the form of a rail, a rod or the like; and in that said first member (21) has a cross-sec¬ tional shape which surrounds the second device either completely or partially; and in that one of said functions is initiated upon relative axial movement between the devices (21, 22) and the other of said functions is initiated upon radial relative movement between the devices.

6. An arrangement according to Claim 1 or Claim 5, characterized in that position detecting means such as potentiometers, Hall elements or the like are mounted on the second device (22) and are activatable pro¬ gressively in response to the relative movement of the first device (21).

7. An arrangement according to Claim 1 or Claim 5, characterized in that one of said functions comprises common activation of two electrically-driven wheels, and in that the other of said functions comprises driving said wheels in an opposite direction.

8. An arrangement according to Claim 1 or Claim 5, characterized in that the first device is provided with means which will engage the control system in response to the grip of the driver's hand and which will disengage the control system when the grip is removed.