GB2525916A

GB2525916A - Service vehicle

Info

Publication number: GB2525916A
Application number: GB1408200.2A
Authority: GB
Inventors: Simon Cave; Carl Jones
Original assignee: G O S TOOL & ENGINEERING SERVICES Ltd
Current assignee: G O S TOOL & ENGINEERING SERVICES Ltd
Priority date: 2014-05-09
Filing date: 2014-05-09
Publication date: 2015-11-11
Anticipated expiration: 2034-05-09
Also published as: GB2525916B; GB201408200D0

Abstract

A service vehicle 1 capable of travelling on both road and rail comprises front 6 and rear 7 wheels each carrying a tyre 8 for engagement with a road and for engagement with the top of a rail and front 9 and rear 10 sets of rail gear. Each set of rail gear 9, 10 comprising a pair of flanged wheels 9, 10 for engaging respective rails of a pair of rails while the road wheels 6, 7 engage the tops of the rails. The flanged wheels 9, 10 of at least one pair of flanged wheels 9, 10 are each mounted on an axle (21, 22, Figure 3) that is connected to the vehicle body via a spherical bearing (23, Figure 3). Preferably angular movement of the axle within the spherical bearing (23) of the flanged wheels 9, 10 is restricted for angular movement about a vertical axis passing through the longitudinal axis of the axle. A method of operating the vehicle 1 is also disclosed which optionally includes the step of when operating the vehicle on a road having the flanged wheels 9, 10 clear of the road.

Description

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service vehicle This invention relates to a service vehicle capable of travelling on both road and rail. Such a service vehicle may be used for a wide variety of purposes, for example to convey material to a site and/or to provide lifting gear at a site. The invention is particularly, but not exclusively, concerned with self-propelled vehicles.

There are two general kinds of such vehicle. A first type has both road wheels with pneumatic tyres and flanged rail wheels: in one, road, mode of operation, the road wheels support the vehicle on the ground and the rail wheels are clear of the ground; in another, rail, mode of operation the rail wheels support the vehicle on a pair of rails and the road wheels are clear of the rails and the ground. A second type has both road wheels with pneumatic tyres and flanged rail wheels: In one, road, mode of operation, the road wheels support the vehicle on the ground and the rail wheels are clear of the ground; in another, rail, mode of operation the road wheels support the vehicle on a pair of rails and rail wheels also engage the rails to keep the vehicle correctly aligned on the rails. The present invention is concerned exclusively with the second type of vehicle.

In such a vehicle it is of course important that in the rail mode of the vehicle the flanged wheels are pressed downwardly onto the rail so that the flanges of the wheels extend down below the tops of the rails on their insides and serve the purpose of maintaining the vehicle on the rails, while propulsion and braking of the vehicle is provided by the tyres of the road wheels engaging the rail.

In a known vehicle of the second type two pairs of flanged rail wheels are provided at the front and rear of the vehicle. Each pair of wheels is carried on a respective axle which is supported on a frame that can be pivoted about a horizontal axis parallel to the longitudinal axis of the axle by a hydraulic actuator.

Since the rails are precisely positioned in order to function effectively for ordinary rail traffic, an arrangement of this kind is generally satisfactory, but there are times when it does not perform well. For example, at a bend in the railway line, there may be a transition of an outer rail to a higher level than an inner rail and as the road-rail vehicle passes round such a bend the loads on the flanged wheels on the different rails may differ considerably. Such unegual load sharing may have various disadvantages such as reduced friction between a road wheel of the vehicle and a rail, high stresses in parts of the structure mollnting the rail wheels, or even derailment of the vehicle.

It is an object of the invention to provide an improved form of service vehicle capable of travelling on both road and rail.

According to the invention, there is provided a service vehicle capable of travelling on both road and rail, the vehicle comprising: front and rear wheels, each carrying a tyre for engagement with a road and for engagement with the top of a rail; and front and rear sets of rail gear, each set comprising a pair of flanged wheels for engaging respective rails of a pair of rails while the road wheels engage the tops of the rails, wherein the flanged wheels of at least one pair of flanged wheels are each mounted on an axle that is connected to the vehicle body via a spherical bearing.

By connecting the axle of the flanged wheels to the vehicle body by a spherical bearing, an extra degree of freedom of movement of the axle is allowed, enabling the loads on each of the flanged wheels to be shared more evenly.

said at least one pair of flanged wheels are preferably mounted on a common axle. The axle may be a single member but it is preferably formed of a main central part and stub axles defining fixed extensions of the main central part. Preferably the stub axles and the main central part are coaxial. The stub axles may be welded to the main central part.

Tt is within the scope of the invention for the axle to be rotatable and the wheels fixed on the axle, but in vehicles of this kind It Is usual for the axle to be fixed; thus, said at least one pair of flanged wheels are preferably rotatably mounted on the axle.

Preferably the angular movement of the axle within the spherical bearing is restricted. The angular movement of the axle within the spherical bearing may be restricted for angular movement about a vertical axis passing through the longitudinal axis of the axle and/or for angular movement about a horizontal axis perpendicular to the longitudinal axis of the axle and/or for angular movement about the longitudinal axis of the axle. Preferably the restricted movement is allowed about all three axes, but it is within the scope of the invention for the movement about one or two of the three axes to be prevented. The movement about different axes may be restricted to the same degree or to different degrees. Tt will usually be preferred that restricted angular movement about one or more of the axes is restricted to total angular movement of less than 10 degrees. in an embodiment of the invention described below, movement is restricted to about 6 degrees about each axis.

The angular movement is preferably restricted by a member engaging a recess or opening in a convex spherical bearing surface and an opening or recess in an opposing surface of a bearing block. The convex spherical bearing surface is preferably disposed concentrically around the axle. The member may be fixed to one of the openings or recesses or may be a separate member.

Each spherical bearing preferably provides a connection between the axle and the distal end of a respective arm connected at its opposite end to the vehicle body, for example to a chassis of the vehicle. The opposite end of the respective arm is preferably pivotally mounted on the vehicle body. The respective arm may be inclined at a shallow angle (less than 45 degrees) to the horizontal; arms at the front of the vehicle may project rearwardly from the vehicle body to the axle; similarly, arms at the rear of the vehicle may project forwardly from the vehicle body to the axle.

The pivoting of the respective arm is preferably controlled by a hydraulically operated actuator. The hydraulically operated actuator may be an extensible link incorporating a piston and cylinder arrangement and pivotally connected at one end to the vehicle body and at the other end to the distal end of the respective arm.

Tt is within the scope of the invention for the vehicle to be provided with only one pair of flanged wheels as defined above but it is preferred that the flanged wheels of each pair of flanged wheels are each mounted on an axle that is connected to the vehicle body via a spherical bearing. Usually there will preferably be four flanged wheels mounted on two axles but further pairs of flanged wheels on further axles may be provided if desired.

The present invention still further provides a method of operating a service vehicle as defined above. The method may include the steps of driving the vehicle on a road with the tyres of the front and rear wheels engaging the road and with the flanged wheels clear of the road, and driving the vehicle on a pair of rails with the tyres of the front and rear wheels engaging the rails and with the flanged wheels also engaging the rails.

By way of example, a service vehicle will now be described with reference to the accompanying schematic drawings, of which: Fig. 1 is a side view of a road-rail vehicle embodying the invention; Fig. 2 is a side view to a larger scale of a part of the vehicle; Fig. 3 is an exploded isometric view of a wheel mounting of the vehicle; and Fig. 4 is a sectional front view of the wheel mounting shown in Fig. 3.

Referring first to Figs 1 and 2, there is shown a road-rail vehicle 1 generally comprising a driver's compartment 2, a load carrying compartment 3, a small crane 4 and a chassis 5 on which front wheels 6 and rear wheels 7, fitted with pneumatic tyres 8 are mounted. Also mounted on the chassis 5 are front flanged wheels 9 and rear flanged wheels 10. It will be understood that there are two of each of the wheels 6, 7, 9 and 10 on opposite sides of the vehicle but only one wheel of each kind is visible in Fig. 1.

The flanged wheels 9 and 10 are mounted on hydraulically operated arms by which they can be raised or lowered. More particularly each flanged wheel Is mounted on the distal end of a respective arm 12 which is pivotally connected to the chassis 5 at a pivot 13. Pivoting of each arm 12 is controlled by a hydraulic actuator 14 which is pivotally connected to the chassis at a pivot 15 and to the distal end of the arm 12 at a pivot 16 (see Fig. 2) . The hydraulic actuator 14 comprises a piston and cylinder arrangement 15 by which the length of the actuator can be altered thereby pivoting the arm 12 to raise or lower the wheel. As can be seen in Figs. 1 and 2, the arms 12 are inclined at a shallow angle (less than 45 degrees) to the horizontal; arms at the front of the vehicle project rearwardly from the vehicle body to the rail wheels; similarly, arms at the rear of the vehicle project forwardly from the vehicle body to the rail wheels.

The vehicle 1 has two modes of travel. In a first mode, for travel on road, the flanged wheels 9 and 10 are raised by the hydraulic actuators 14 to a position higher than that shown in Fig. 1 so that they are clear of the ground and the whole weight of the vehicle is supported on the wheels 6 and 7 fitted with the pneumatic tyres 8; in this first mode the vehicle is operated very much as a conventional road vehicle. In a second mode, for travel on rail, the flanged wheels 9 and 10 are lowered to the positions shown in Fig.1; in this mode the pneumatic tyres of the wheels 6 and 7 bear down on the tops of a pair of rails supporting most of the weight of the vehicle and the flanged wheels 9 and 10 also bear against the wheels with flanges 18 of the wheels on the inside of each rail. The flanged wheels 9 and 10 thereby maintain the vehicle aligned on the rails.

The vehicle as described above is known per se. The present invention is concerned with the manner in which the flanged wheels 9 and 10 are mounted and will now be described with reference to Figs. 3 and 4 which shows the mounting of one of the front flanged wheels 9.

The wheel 9 is rotatably mounted on a stub axle 21 which is welded to a main axle 22 with whioh it is coaxial.

Formed on the exterior of the stub axle 21 is a spherical bearing surface 23 which is received in a bearing block 24 having an inner surface 25. The bearing block 24 is in two halves; a first half 24A is fixed to the distal end of the arm 12 and a second half 24B is bolted to the first half 24A after insertion of the axle 21 and half bearings 26 which engage the bearing surface 23 of the axle 21 mounting it for angular movement about all three orthogonal axes.

A key 28 is also fitted during assembly of the two halves of the bearing block, the key 28 being received partly in a slot-shaped recess 29 in the inner surface 25 of the first half 24A of the bearing block 24 and partly in a similar slot-shaped recess (not visible in the drawings) in the bearing surface 23 of the axle 21. The key 28 is a loose fit in the slot-shaped recesses and therefore restricts, but does not prevent, angular movement of the axle 21 about all three orthogonal axes. The degree of restriction is of course determined by the dimensions of the key and the slot-shaped recesses. In one particular example of the invention, the angular movement is restricted to a total movement of about 6 degrees about any axis.

Tt should be understood that the mounting of the other flanged wheels 9 and 10 is substantially the same as that just described.

Tn operation, when the vehicle 1 is on rails that are straight and level, each axle 21 is exactly horizontal and exactly perpendicular to the rails and each key 28 is in the centre of its respective slot-shaped recesses. When, for example, one rail rises above the other, for example at a bend, the axle will try to move away from a precisely horizontal position and/or a position precisely perpendicular to the rails. In a conventional arrangement that would lead to stresses and strains within the axle and the arms mounting the axle to accommodate the height difference, but with the spherical bearing those stresses and strains can be largely or totally accommodated by small angular movement of the axle 21 within the bearing.

Whilst one particular example of the invention has been described with reference to the drawings, it should be understood that many modifications may be made within the scope of the invention. For example the vehicle may take a wide variety of forms according to the activity it is to perform. Whilst in the illustrated embodiment the vehicle has four road wheels and four rail wheels, it will be understood that other arrangements are possible; for example the vehicle might have more than four road wheels with only some or all of the wheels being operative when the vehicle is being driven along rails.

Where in the foregoing description, integers or

elements are mentioned which have known, obvious or -10 -foreseeable equivalents, then such equivalents are herein incorporated as if individually set forth. Reference should be made to the claims for determining the true scope of the present invention, which should be construed so as to encompass any such equivalents. It will also be appreciated by the reader that integers or features of the invention that are described as preferable, advantageous, convenient or the like are optional and do not limit the scope of the independent claims.

Claims

-11 -Claims: 1. A service vehicle capable of travelling on both road and rail, the vehicle comprising: front and rear wheels, each carrying a tyre for engagement with a road and for engagement with the top of a rail; and front and rear sets of rail gear, each set comprising a pair of flanged wheels for engaging respective rails of a pair of rails while the road wheels engage the tops of the rails, wherein the flanged wheels of at least one pair of flanged wheels are each mounted on an axle that is connected to the vehicle body via a spherical bearing.
2. A service vehicle according to claim 1, in which said at least one pair of flanged wheels are mounted on a common axle.
3. A service vehicle according to claim 2, in which said at least one pair of flanged wheels are rotatably mounted on the axle.
4. A service vehicle according to any preceding claim, in which the angular movement of the axle within the spherical bearing is restricted.
5. A service vehicle according to claim 4, in which the angular movement of the axle within the spherical bearing is restricted for angular movement about a vertical axis passing through the longitudinal axis of the axle.
6. A service vehicle according to claim 4 or 5, in which the angular movement of the axle within the spherical -12 -bearing is restricted for anguiar movement about a horizontal axis perpendicular to the longitudinal axis of the axle.
7. A service vehicle according to any of claims 4 to 6, in which the angular movement of the axle within the spherical bearing is restricted for angular movement about the longitudinal axis of the axle.
8. A service vehicle according to any of claims 4 to 7, in which the restricted angular movement about one or more of the axes is restricted to total angular movement of less than 10 degrees.
9. A service vehicle according to any of claims 4 to 8, in which the angular movement is restricted by a member engaging a recess or opening in a convex spherical bearing surface and an opening or recess in a corresponding concave spherical surface of a bearing block.
10. A service vehicle according to claim 9, in which the convex spherical bearing surface is disposed concentrically around the axle.
11. A service vehicle according to any preceding claim, in which each spherical bearing provides a connection between the axle and the distal end of a respective arm connected at its opposite end to the vehicle body.
12. A service vehicle according to claim 11, in which the opposite end of the respective arm is pivotally mounted on the vehicle body.
13. A service vehicle according to claim 12, in which the pivoting of the respective arm is controlled by a -13 -hydraulically operated actuator.
14. A service vehicle according to claim 13, in which the hydraulically operated actuator is an extensible link incorporating a piston and cylinder arrangement and pivotally connected at one end to the vehicle body and at the other end to the distal end of the respective arm.
15. A service vehicle according to any preceding claim, in which the flanged wheels of each pair of flanged wheels are each mounted on an axle that is connected to the vehicle body via a spherical bearing.
16. A service vehicle capable of travelling on both road and rail, the vehicle being substantially as herein described with reference to the accompanying drawings.
17. A method of operating a service vehicle according to any preceding claim.
18. A method according to claim 17, including the steps of driving the vehicle on a road with the tyres of the front and rear wheels engaging the road and with the flanged wheels clear of the road, and driving the vehicle on a pair of rails with the tyres of the front and rear wheels engaging the rails and with the flanged wheels also engaging the rails.