GB2053333A

GB2053333A - Improvements in and relating to a ladder gantry

Info

Publication number: GB2053333A
Application number: GB8019679A
Authority: GB
Original assignee: ANGUS SACOL LADDERS Ltd
Current assignee: ANGUS SACOL LADDERS Ltd
Priority date: 1979-06-29
Filing date: 1980-06-17
Publication date: 1981-02-04
Also published as: GB2053333B

Abstract

Ladder retention means typically suitable for use on a fire appliance vehicle to restrain any tendency for an extension ladder to slide off a support gantry on the top of the vehicle comprises a rigid body portion and a locking member. The rigid body portion receives a location member extending outwards beyond a side of a ladder and the locking member serves to retain the location member housed in the rigid body portion.

Description

SPECIFICATION Improvements in and relating to a ladder gantry This invention relates to a ladder gantry, known sometimes as ladder gallows, and in particular, though not exclusively, to a gantry for securing an extension ladder to the top of a fire appliance vehicle.

Fire appliance vehicles commonly carry extension ladders comprising two or three sections each of 1 5 feet in length. Despite the light weight materials used the resulting ladder assembly is often relatively heavy and awkward to stow on the vehicle. In addition the weight of the ladder is increased if provided with hinged side legs for ease of handling and stabilisation of the ladder when extended; similarly the lower ladder section commonly incorporates a base stabilisation bar extending outwards beyond the sides of the ladder and having jacking devices to enable the ladder to be set vertical on uneven ground, and this also increases weight.

To facilitate ready removal of the ladder from the top of a fire appliance vehicle, and subsequent replacement, it is common practice to provide on the top of the appliance a gantry having rollers over which the ladder may relatively easily be moved despite its weight. The gantry also supports the ladder in a position inclined downwards, towards one end of the gantry, so that the ladder will easily move down the gantry for removal at said end.

To To restrain the ladder from sliding off the gantry because of its inclined position and forces resulting from acceleration and braking of the vehicle it is necessary to provide safe and secure retention means to hold the ladder in place. One conventional type of retention means comprises hinged metal arms which pass over part of the ladder and are held in position by locking bars.

This arrangement cannot always be relied on to ensure that the ladder is safely and securely located, and has several other disadvantages including being slow to release and secure.

An object of the present invention is to provide improved means for safely retaining a ladder on a vehicle gantry.

In accordance with one aspect of the present invention ladder retention means for retaining a ladder on a ladder gantry comprises a rigid body portion for receiving a location member extending outwards beyond a side of a ladder, and a locking member for retaining said location member housed in the rigid body portion.

Preferably the locking member is inherently biased to a locking position, for example by the action of gravity, during normal use, or by spring means.

The rigid body portion preferably is in the form of a socket which is substantially C-shaped at least at an inner surface so as to house, and conform at least in part to the outer surface of, a base stabilisation bar, or like location member extending outwards beyond a side of a ladder.

Typically the body portion may be formed as a casting e.g. of aluminium, but other materials such as moulded plastics may be used. Especially where the body portion is of metal, preferably an inner surface of the body portion is provided with a layer of cushioning material so as to avoid direct metal to metal contact with the stabilisation bar or like location member.

Preferably the locking member is arranged so as to be automatically depressed during movement of the location member into the body portion and to then return under the action of the spring means or gravity to lock the location member in position until manually released.

The locking member may be pivotally mounted in order to permit its depression on insertion of the location member, it pivoting back to its initial locking position under the action of the spring means or gravity when the location member is housed in the rigid body portion. Preferably the pivotally mounted locking member is shaped, e.g.

in the form of an over-centre cam, such that any forces exerted thereon by the location member tending to move out from the body portion urge the locking member to further close the opening in the rigid body portion.

The locking member preferably is mounted on and wholly supported by said rigid body portion, and preferably has secured thereto or formed integrally therewith release means such as a handle to facilitate movement of the locking member to an open position when it is desired to release the stabilisation bar, or like location member, and remove the ladder from the gantry.

Instead of being secured to or integral with the locking member the release means may be independent and for example controllable selectively to engage the locking member to effect movement thereof.

Where the locking member is inherently biased by spring means preferably the pivotal mounting of the locking means and associated handle is arranged in combination with the weight and shape of said components such that in the event of failure of the spring means the locking member pivots freely to a locking position. That is, normally the locking member is inherently biased to a locking position both by gravity and the spring means.

The present invention further provides a ladder gantry and a fire appliance vehicle having a ladder gantry comprising said improved ladder retention means.

Preferably the gantry comprises two of said retention means spaced apart for receiving respective end portions of a ladder base stabilisation bar or like location members. The provision of two retention means ensures that an end of a ladder is more securely located, especially against vertical movements, and with double the degree of safety than if only one retention means is employed.

One embodiment of the invention will now be described, by way of example only, with reference to the accompanying diagrammatic drawings in which : Figure 1 is a part-sectional side view of part of a fire appliance vehicle and ladder gantry with retention means in accordance with the present invention; Figure 2 is a perspective view of an extension ladder for location in the gantry of Figure 1; Figure 3 is a perspective view of the retention means shown in Figure 1; Figure 4 is a perspective view of a further part of the ladder gantry shown on Figure 1; Figure 5 is a side view of one of the head end stops shown in Figure 4, and Figure 6 is a perspective view of another head end stop.

A fire appliance vehicle 10 comprises a head gantry unit 11, mid gantry unit 12, and rear gantry unit 13 for supporting an extension ladder 14.

The head gantry unit 11 incorporates a pair of spaced apart low friction runners 1 5 for supporting the leading end of that ladder section which lies lowest in position on top of the vehicle (normally the top or narrowest section of the ladder). Said head unit 11 also incorporates a pair of spaced end stops 1 6 (see Figures 4 and 5), which are designed, as described in more detail below, to bear on an end of the lowest ladder section and thereby assist in securing the ladder assembly to the vehicle.

The end stops 16 are of a multipurpose design so as to accommodate different types of ladders.

In one type of ladder the upper end of the top ladder section is provided with a pair of spaced wall wheels 18 (see Figure 2) supported by an axle 19 which extends across an end of the ladder section; said wheels facilitate movement of the ladder on the wall of a building. In the case of this type of ladder the end stops may bear against the wheel axle.

In ladders of a type which do not incorporate wall wheels the end stops may be required to bear against a ladder rung which is typically of a greater cross-section than an axle.

Each end stop 16 comprises a substantially Cshaped metal frame 40 relative to which a restraint cam 41 is pivoted. The restraint cam has a first indented edge portion 42 under which a wall wheel axle 1 9 may pass as a ladder is slid into position. The cam also has a second indented edge portion 43 which is swung clockwise as viewed in Figure 4 when engaged by a ladder rung. In either position the indented shapes of said first and second edge portions, the C shape of the frame 40, and the relative positioning of the pivot 44 assist in ensuring that the ladder is secured against forward and vertical movement by the head gantry unit. In an alternative construction the cam may have three or more indented edge portions respectively for retention of three or more different types of ladder ends.The end stop 16 may alternatively have the restraint cam mounted to one side of the support frame as illustrated in Figure 6. In Figure 6 there is shown a head end stop which comprises a cast support frame 50 having pivotally secured thereto a nylon cam 51 formed with two indented edge portions 52, 53.

The mid and rear gantry units 12, 13 each comprise a pair of spaced apart support rollers 1 7 (see Figure 1) on which run the side pieces of that ladder section which lies lowest in position on top of the vehicle. The rollers are flanged and thus further serve to locate the ladder transversely of the vehicle.

The rear gantry unit 13 additionally comprises a pair of spaced retention members 20 which are described in more detail below. The retention members are spaced apart by a distance greater than the spacing of the support rollers 1 7 of each pair so that with the exception of the ladder base stabilisation bar 21, the ladder assembly is able to pass between the two retention members. Each retention member 20 is bolted to a pedestal mounting 22 which in turn is fixed to the vehicle body. In this embodiment the spacing of the retention members is such that each engage the base stabilisation bar at a position mid-way between a side piece of the lower ladder section and a levelling unit 23.

The retention members 20 are now described in more detail with reference to Figure 3. Each retention member comprises a substantially Cshaped cast aluminium housing socket 24 having a pair of limb portions 25,26 spaced apart to define an opening 27 through which a base stabilisation bar 21 may be received. The inner surface of the socket has a protective lining 28 of woven belting.

One of the limb portions, a lower limb portion 26, is forked and a locking member in the form of a cam 29 is pivotally mounted relative to said fork. The cam is attached to an end of a handle 30 which, on the vehicle, extends vertically downwards, and a coil spring 31 extends between the handle and socket casting so as normally to bias the cam to a closed position in which it partly occupies the opening 27 between the limb portions.

The closed position of the cam is determined by abutment of part of the cam against the forked lower limb portion 26, and it is normally held in that position by the spring 31 which remains under tension.

The cam has a first edge 32 which extends substantially radially relative to the pivot and a second edge 33 which extends substantially tangentially. When the base stabilisation bar 21 is inserted in the housing socket 24 it bears against the first cam edge 32 and causes the cam and handle to pivot anti-clockwise, as viewed from the left in Figure 3, against the tension in the spring 31. When the bar 21 is fully inserted the spring assists the cam to return to the closed position at which the spring is under light tension.

If the stabilisation bar tends to move backwards it bears against the second cam edge 33. This edge is of an over centre type of profile and any force exerted thereon by the bar urges the cam to tend to further close the opening.

To effect release of the stabilisation bar 21 the two handles 30 of the two retention members are moved backwards, i.e. away from the rear of the vehicle, so as to swing the cams downwards.

Provision of separate handles on each retention means 20 ensures that inadvertent release is unlikely. Alternatively however, the two cams of the two retention means may be interconnected so as to be operable by a single common handle.

From the foregoing it will be understood that the present invention permits ready release of a ladder from a gantry, and automatic locking in position on stowage, whilst also ensuring that the ladder is safely secured in position for transit.

Claims

1. Ladder retention means for retaining a ladder on a ladder gantry comprising a rigid body portion for receiving a location member extending outwards beyond a side of a ladder, and a locking member for retaining said location member housed in the rigid body portion.

2. Ladder retention means according to Claim 1 wherein the locking member is inherently biased to a locking position.

3. Ladder retention means according to Claim 2 wherein the locking member is inherently biased by the action of gravity.

4. Ladder retention means according to Claim 2 wherein the locking member is biased by spring means.

5. Ladder retention means according to any one of the preceding claims wherein the rigid body portion is in the form of a socket at least an inner surface of which is substantially C-shaped.

6. Ladder retention means according to any one of the preceding claims wherein an inner surface of the body portion is provided with a layer of cushioning material.

7. Ladder retention means according to any one of the preceding claims wherein the locking member is automatically depressed during movement of a ladder location member into the body portion.

8. Ladder retention means according to any one of the preceding claims wherein the locking member is pivotally mounted.

9. Ladder retention means according to any one of the preceding claims wherein the locking member comprises an over-centre cam which tends normally to further close the opening in the rigid body portion in response to any tendency of the ladder location member to move out from the body portion.

10. Ladder retention means according to any one of the preceding claims wherein the locking member is mounted on the rigid body portion.

11. Ladder retention means according to Claim 10 wherein the locking means is wholly supported by the rigid body portion.

12. Ladder retention means according to any one of the preceding claims wherein release means associated with the locking member inherently tends to bias the locking member to a locking position.

13. Ladder retention means according to any one of the preceding claims wherein release means is formed integrally with the locking means.

14. Ladder retention means according to Claim 12 or Claim 13 wherein the release means is in the form of a handle.

1 5. Ladder retention means constructed and arranged substantially as hereinbefore described with reference to the accompanying drawings.

16. A ladder gantry comprising ladder retention means according to any one of the preceding claims.

17. A ladder gantry according to Claim 16 comprising two ladder retention means spaced apart for receiving respective location members extending from the sides of a ladder.

18. A ladder gantry according to Claim 16 or Claim 1 7 wherein an inner surface of the rigid body portion of the ladder retention means conforms at least in part to the outer surface of a location member extending from a ladder carried by said gantry.

19. A ladder gantry constructed and arranged substantially as hereinbefore described with reference to the accompanying drawings.

20. A fire appliance vehicle comprising a ladder gantry according to any one of Claims 16 to 19 positioned to support a ladder in a position inclined to the horizontal and parallel with the normal direction of travel of the vehicle.