GB2227993A - Riser post arrangement for elevating access platform - Google Patents

Abstract

Access platform apparatus has modified geometry whereby a more compact assembly can be achieved in the stowed or transport position. This is achieved by arranging that the riser post 20, which interconnects the riser boom 22 and the platform boom 24, extends upwardly and forwards at an inclination of more than 3 degrees to the vertical, instead of the usual generally vertical attitude. As a result, in the stowed position, the platform boom main pivot 52 is located significantly further forwards than is otherwise possible, thereby reducing the overall length of the apparatus. <IMAGE>

Description

ACCESS PLATFORMS This invention relates to access platforms of the kind in which a platform, for example to provide a stable surface on which a technical operative can stand to effect maintenance operations on high level structures, is mounted on a boom and is elevatable and may be swingable or otherwise position-adjustable by power means. Access platforms of this kind are often mounted or are mountable or trucks or specialists vehicles. An example of such an access platform is shown in the accompanying drawings. The invention may also be applicable to other boom type elevating apparatus.

In the case of presently available access platform apparatus it is commonly the case that in the lowered or retracted or transport position of the apparatus it is necessary for the booms to be stowed and positioned so as not to conflict with or foul fixed structures, such as a vehicle cab, provided adjacent the access platform apparatus. Since such structures as vehicle cabs have a not inconsiderable height and the riser boom of the apparatus necessarily describes an arc as it is raised and lowered, the centre of the arc being located at the top of the base post or first post of the apparatus (which itself is at a predetermined height from the base of the apparatus), there are resulting spacial consequences which lead to the apparatus having an overal length in its stowed or retracted or transport position, which is greater than could be desired.

An object of the present invention is to provide improvements in relation to one or more of the matters discussed herein, or generally.

According to the invention there is provided an access platform and boom type elevating apparatus as claimed in the accompanying claims.

In a preferred embodiment access platform apparatus comprises a first post and a riser post. A riser boom pivotally interconnects the posts and a platform boom is pivotally connected to the riser post and has a platform mounted on it. Actuating means for the booms is provided to effect elevation of the platform. A notable feature of the apparatus is that a line between the pivots connecting the booms to the riser post is inclined with respect to the vertical at more than 3 degrees, in the lowered position of the booms.

In a preferred embodiment, boom type elevating apparatus is provided in which the line between the pivots connecting lower and upper booms to a riser post is inclined with respect to the vertical at more than 3 degrees in the lowered position of the booms.

The riser boom comprises a parallelogram linkage whereby the first and riser posts are maintained in a relatively constant angular relationship during lifting and lowering of the platform, and thus the inclination of said line is likewise maintained relatively constant. The inclination of the line may lie in the range of 5 to 35 degrees and preferably in the range 10 to 30 degrees.

The access platform apparatus is mounted on a vehicle, and the first post is mounted at a rearward portion of the vehicle with respect to its direct of forward motion. In a transport position of the apparatus the riser boom extends forwardly towards an upstanding fixed structure (such as a vehicle cab), and the inclination of the line between the pivots is forwards and upwards with respect to said direction of forward motion of the vehicle, and passes said fixed structure with a predetermined clearance.

In another preferred embodiment the first or base post is usually mounted for rotatable movement and is fixed to a base frame and carries the various elevating parts of the apparatus. The riser boom, including a riser brace or link is pivotally connected to the base post at one end, and to the riser post at its other end. The four pivots of the riser boom define an articulating parallelogram linkage. This embodiment includes a platform boom, by way of example.

To lift the booms there are provided power-extendable components, usually but not exclusively hydraulic cylinders. These act between the posts and their associated booms.

In the preferred embodiment, by inclining the riser post at a suitable inclination, the potential collision point between the riser post and (for example) a vehicle cab is shifted so that a more compact design results. The increased compactness achieved can be used to provide a longer platform boom within the same overall length of apparatus.

Previous proposals have included riser posts in which a minor inclination with respect to the vertical may exist.

Likewise, access platforms may have been provided in which the first or base post is not vertical, and likewise a post mounted on the platform itself. It will be appreciated that these latter factors are of no relevance to the clearance and overall length questions with which the present invention is concerned.

An embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which : Fig 1 shows a side elevation view of access platform apparatus to provide a basis for comparison when describing the embodiment of the invention with reference to Fig 2; and Fig 2 shows, in a view similar to Fig 1, an embodiment of the invention.

The apparatus shown in Figs 1 and 2 are substantially the same in most major respects, except so far as concerns features relating to the invention as such. Therefore, the same reference numerals will be utilised for both sets of apparatus, except where necessary to distinguish the embodiment of the invention, as shown in Fig 2, from the apparatus of Fig 1.

As shown in the drawings, access platform apparatus 10 is mounted on a vehicle 12 in the form of a truck body having a platform 14 and a driver's cab 16. The direction of normal forward movement is indicated by F. In the drawings, the access platform apparatus is shown in its stowed or transport or lowered position.

Apparatus 10 comprises a first post 18, a riser post 20, a riser boom 22, a platform boom 24, a platform 26, and actuating means 28, 30 for the booms, in the form of hydraulic rams.

Base post 18 is mounted for turning movement about its generally vertical longitudinal axis under the control of a further hydraulic ram (not shown).

Riser boom 22 comprises a main boom link 32 and a bracing link 34. The end pivots of boom 22 are identified as 36, 38 and 40, 42.

Rams 44 and 48 are provided for co-ordinated actuation to maintain platform 26 generally level during raising and lowering operations. The main component 46 of platform boom may be constructed in telescopic form for powered actuation, whereby end portion 50 of the boom is moved forwards and rearwards.

It will be noted that platform boom 24 is pivotally connected to riser boom 20 at pivot 52.

It will be noted in Fig 2 that the line 54 which extends between the pivots 40 and 52 connecting the booms 22 and 24 to riser post 20, is inclined with respect to the vertical at more than 3 degrees in the lowered position of the booms, as shown in Fig 2. In this embodiment, the angle 56 between line 54 and the horizontal 58 (ie the ground surface is 70 degrees, and thus the inclination to the vertical is 20 degrees. As a result, the position of pivot 52 is almost directly over the rear surface of cab 16. This fact is particularly to be noted for the purposes of comparison with the apparatus shown in Fig 1.

It will be seen in Fig 2 that riser post 20 has a clearance 60 from the top rear edge of cab 16, and that the arcs of movement of the end pivots 40, 42 of riser boom 22 are shown at 62 and 64.

Turning now to the apparatus shown in Fig 1 for comparison purposes, it will be seen that the main area of difference lies in the structure and arrangement of the riser post 20A. As shown, the post 20A is approximately vertical in its stowed or transport position, and the line 54A joining the pivots 40A and 52A is at an angle 56A with respect to the horizontal 58 of about one right angle (in this particular apparatus the angle 56A is 88.5 degrees).

Thus, the inclination with respect to the vertical is 1.5 degrees.

The result of this arrangement can be readily seen.

In order to provide adequate clearance 60A between the cab 16 and the point 66 at the forward end of riser boom 22 as the latter passes the cab (see arcs of movement 62A, 64A), it is necessary to locate the pivot 52A significantly rearwardly of the position of the pivot 52 in the embodiment of the invention shown in Fig 2. As a result, the rear end 68A of the apparatus in Fig 1 is located a distance 70 further rear wards than end 68 in Fig 2. In other words, the overall vehicle length is increased by this amount even though the dimensions of all major components of the apparatus in Fig 1 are the same as those in Fig 2 ie the boom lengths, post lengths etc. Thus, by means of the disposition or inclination of the riser post exemplified in Fig 2, a significant saving in overall space has been achieved. This is of considerable significance to users.

In the above embodiment, the riser boom 22 is in the form of a parallelogram linkage having double pivots at each end. As regards the line between the pivots connecting the booms to the riser post, the relevant pivot chosen for the purpose of the line 54 is the pivot 40 which, as the boom is raised, passes nearer to the rear top edge of cab 16, in this case pivot 40. Where the riser boom has only a single pivot at each end (and alternative means to control the attitude of riser post 20), this point does not arise.

Claims (7)

CLAIMS :

1 Access platform apparatus comprising a) a first post; b) a riser post; c) a riser boom pivotally interconnecting said first post and said riser post; d) a platform boom pivotally connected to said riser post; e) a platform mounted on said platform boom; and f) actuating means for said booms to effect elevation of said platform; characterised in that g) a line between the pivots connecting said booms to said riser post is inclined with respect to the vertical at more than 3 degrees in the lowered position of said booms.

2 Boom type elevating apparatus in which a line between the pivots connecting lower and upper booms to a riser post is inclined with respect to the vertical at more than 3 degrees in the lowered position of said booms.

3 Apparatus according to claim 1 or claim 2 characterised in that said riser boom comprises a parallelogram linkage whereby said first and riser posts are maintained in a relatively constant angular relationship during lifting and lowering of the platform, and thus said inclination of said line is likewise maintained relatively constant.

4 Apparatus according to any one of claims 1 to 3 characterised in that said inclination of said line lies in the range of 5 to 35 degrees with respect to the vertical.

5 Apparatus according to any one of claims 1 to 4 characterised in that said inclination of said line lies in the range of 10 to 30 degrees with respect to the vertical.

6 Apparatus according to any one of claims 1 to 5 characterised in that said apparatus is mounted on a vehicle and said first post is mounted at a rearward portion of said vehicle, with respect to the direction of forward motion of the vehicle, and in a transport position of said apparatus said riser boom extends forwardly towards an upstanding fixed structure (such as a vehicle cab) of said vehicle, and the inclination of said line between said pivots is generally forwards and upwards with respect to said direction of forward motion of the pehicle and passes said fixed structure with a predetermined clearance.

7 Access platform apparatus substantially as described herein with reference to and as shown in Fig 2 of the accompanying drawings.