US3891056A

US3891056A - Hydraulically elevatable platforms

Info

Publication number: US3891056A
Application number: US440552A
Authority: US
Inventors: Denis Henry Ashworth
Original assignee: Simon Engineering Dudley Ltd
Current assignee: Simon Engineering Dudley Ltd
Priority date: 1973-02-21
Filing date: 1974-02-07
Publication date: 1975-06-24
Anticipated expiration: 1992-06-24
Also published as: GB1458506A; BE811162A; DE2408405A1; CA992470A; FI53564C; SE390721B; AT351706B; ATA142874A; FI53564B

Abstract

Access equipment of the kind comprising an articulated boom structure which consists of a first boom pivotally and preferably rotatably mounted on a vehicle or like supporting structure, and at least one further boom pivotally connected to the free end of the first boom, hydraulic actuating cylinders being provided for effecting relative pivotal movement of the booms one to the other, and both to the supporting structure, means being associated with each boom and movable therewith for transmitting movements of the booms individually and collectively to a plurality of stops which are thus movable to actuate control valves for the hydraulic actuating cylinders, the stops being arranged in response to movements of the booms and in accordance with permitted degrees of pivotal movement thereof to arrest operation of the actuating cylinders as appropriate to prevent the boom structure assuming a potentially unstable configuration.

Description

States atent n91 Unite Ashworth [111 3,891,056 1 June 24, 1975 Denis Henry Ashworth, Dudley, England [73] Assignee: Simon Engineering Dudley Limited, Cheshire, England 22 Filed: Feb. 7, 1974 211 Appl. No.: 440,552

[75] Inventor:

Primary Examiner-Reinaldo P. Machado Attorney, Agent, or FirmNorris and Bateman 5 7] ABSTRACT Access equipment of the kind comprising an articulated boom structure which consists of a first boom pivotally and preferably rotatably mounted on a vehicle or like supporting structure, and at least one further boom pivotally connected to the free end of the first boom, hydraulic actuating cylinders being provided for effecting relative pivotal movement of the booms one to the other, and both to the supporting structure, means being associated with each boom and movable therewith for transmitting movements of the booms individually and collectively to a plurality of stops which are thus movable to actuate control valves for the hydraulic actuating cylinders, the stops being arranged in response to movements of the booms and in accordance with permitted degrees of pivotal movement thereof to arrest operation of the actuating cylinders as appropriate to prevent the boom structure assuming a potentially unstable configuration.

11 Claims, 4 Drawing Figures PATENTEDJlm24 1975' 3.891; 056

SHEET 1 HYDRAULICALLY ELEVATABLE PLATFORMS This invention concerns access equipment of the kind (hereinafter termed of the kind referred to) comprising an articulated boom structure consisting of a first boom pivotally and preferably rotatably mounted on a vehicle or like supporting structure, and at least a second boom pivotally connected to the free end of said first boom, hydraulic actuating cylinders being provided for effecting pivoting movement of the second boom relative to the first and both booms relative to the supporting structure.

It is essential to ensure that relative movement of the booms does not create a potentially unstable condition, i.e., when a vertical line from the combined centres of gravity of the various parts of the boom structure falls outside the area occupied by the supporting structure. In order to avoid such instability it is necessary to limit the degree of movement of each boom according to said area and to the position of one or more of the other booms.

Furthermore, it is considered important to ensure that movement of any boom is not suddenly arrested at its permitted limit, or at the ends of the stroke of the hydraulic actuating means.

An object of the invention is to provide access equipment of the kind referred to, wherein movement of the booms into a potentially unstable condition is prevented, and preferably wherein permitted movements are progressively retarded to prevent sudden arrest thereof at the permitted limits.

According to the present invention, there is provided access equipment of the kind referred to, wherein means are associated with each of said booms and movable therewith for transmitting movements thereof individually and collectively to stops which are movable to actuate control valves for said hydraulic actuating cylinders, said stops thus being arranged in response to movements of said booms and in accordance with permitted degrees of pivotal movement thereof to arrest operation of said actuating cylinders as appropriate to prevent the boom structure assuming a potentially unstable configuration.

An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

FIGS. 1 and 2 show schematically a boom structure in two operational positions;

FIG. 3 is an elevation of a link system connected to said boom structure and having stop means in accordance with the invention;

and FIG. 4 is a plan view of the arrangement shown in FIG. 3.

Referring now to FIGS. 1 and 2, an articulated boom structure comprises in this case two main booms l and 11 hereinafter referred to as first and second booms respectively, and a shorter auxiliary boom 12 having a cage or working platform 13 pivotally mounted at the outermost end thereof. The lowermost or innermost end of the first boom is pivotally mounted on a turntable 9 for rotation relative to a supporting structure such as a vehicle (not shown).

A parallelogram linkage system is provided for maintaining the cage 13 level for all positions of the boom structure. This system comprises three

levelling rods

14, 17 and 19 forming parallelograms respectively with said first, second and auxiliary booms.

Actuating means comprising

hydraulic cylinders

20 and 20a are provided for elevating the first boom relative to the turntable 9 and the second boom relative to the first. The cylinder 20a operates a rod 21 connected to the second boom, a rod 22 being pivotally connected at one end to the rod 21 part way along its length, and at the other end to said first boom 10. The cylinder 20, rod 21 and rod 22 are positioned along the longitudinal centre line of the boom structure. A pivot shaft 23 to which the rod 22 is attached extends outwardly through the wall of the boom 10 and has attached to one end a first connecting link 24. A second connecting link 25 is pivotally attached to the link 24 and extends back along the side of the boom 10 towards the turntable 9. The end of the link 25 remote from the link 24 is pivotally connected to one end of a common link 26, the other end of which is pivotally connected to the lower levelling rod 14 associated with the boom 10.

It will be appreciated that upwards or downwards movement of the second boom 11 is transmitted to the common link 26 via rod 2], rod 22, shaft 23, connecting link 24 and connecting link 25, and that upwards or downwards movement of the first boom 10 is transmitted to the common link 26 via the lower levelling rod 14.

Referring now to FIGS. 3 and 4, a driving link 27 pivotally connected at one end to the upper end of the common link 26 is connected at its other end to a driving arm 28. The arm 28 is pivotally mounted at its lower end on a shaft 30 attached to the boom 10, and carries

striking abutments

29 and 29a adjacent the shaft 30.

Also, pivotally connected to the link 26 at approximately its mid-point, is one end of a further driving link 31 which, at its other end, is connected to a further driving arm 32 part way along its length. The arm 32 is also pivotally mounted on shaft 30, and there is a corresponding driving arm 32a spaced therefrom and pivotally mounted on a shaft 33 also attached to boom 10. Interconnecting the upper ends of the driving

arms

32, 32a is a rod 34 which carries four stops or strikers A, B, C and D.

A further pair of driving

arms

35 and 36 pivotally mounted on shaft 30 and ashaft 37 respectively are interconnected at their upper ends by a rod 38 which carries two further stops or strikers E and F spaced apart along its length.

A still further pair of driving

arms

39 and 40 are pivotally mounted on

shafts

37 and 33 respectively, and are interconnected at their upper ends by a rod 41 which carries two further stops or strikers G and H spaced apart along its length.

Driving

arms

36 and 39 are normally retained in the positions shown in FIGS. 3 and 4 by springs 42.

The driving

arms

28, 32, 32a, 35, 36, 39 and 40 are all separately and freely rotatable on their associated

shafts

30, 33 and 37.

Two further abutments X and Y are mounted in spaced apart relationship directly on levelling rod 14 and extend into the line of pivoting movement of the arm 39.

The strikers A to H, all of which are preferably adjustable in position on their respective rods for the purpose of setting up the apparatus, are operatively disposed adjacent control levers and 51 pivotally mounted respectively on shafts 52 and 53, and adapted to actuate the hydraulic cylinders for raising and lowering the first and second booms respectively. Movement of the lever 50 to the left and right in FIG. 4 causes the first boom to be lowered and raised respectively. Movement of the lever 51 to the left and right in FIG. 4 causes the second boom to be raised and lowered respectively.

The system so far described is adapted to ensure that the boom structure can never be moved into a potentially unstable condition, such as would be created when a vertical line from the combined centres of gravity of the parts of the boom structure falls outside an area bounded by the supporting structure, which latter normally comprises a vehicle having stabilising jacks.

The positions of the parts as shown in FIGS. 3 and 4 is for a condition when both booms l and 11 are in a stowed position, i.e., both horizontal and in superimposed relationship.

If the second boom 11 is raised, with the first boom remaining in a horizontal position, the lever 51 being at its left hand limit of movement, the connecting link 25 attached indirectly to the rod 22 is moved to the right in FIGS. 3 and 4. If the lower boom is stationary the levelling rod 14 is also stationary so that the link 26 is pivoted in a clockwise direction causing links 31,

arms

32 and 32a, rod 34 and stops A, B, C and D all to move to the right. The relative dimensions of the various moving parts of the system are so arranged that, as the second boom 11 approaches its permitted limit of elevation, the stop C on the rod 34 contacts the control lever 51, returning it gradually to a central position, and thus retarding and finally arresting elevation of the boom.

If the first boom 10 is raised, the lever 50 being at its right hand limit of movement, the lower levelling rod 14 is moved to the left. The link 26 thus pivots in a clockwise direction about its upper end, causing the stop C to move away from control lever 51, allowing further elevation of the second boom 11 if required. If the first boom 10 approaches a position causing the second boom 11 or auxiliary boom 12 or cage 13 to contact the ground or platform mounting, the stop B on rod 34 contacts the control lever 50 returning it once again gradually to a central position. Further elevation of the second boom, however, moves stop B away from control lever 50, thus allowing further elevation of the first boom if required.

It will be seen, therefore, that the combined movements of the two booms are transmitted by link 26 to the rod 31 which, according to the conditions prevailing, move stops A, B, C and D towards or away from control levers 50 and 51 to maintain a stable condition of the boom structure, thus stop A controls downward movement of the lower boom 10, and stop D controls downward movement of the upper boom 11, as necessary.

Stops A, B, C, and D serve as described to control the degree of movement of booms 10 and 1 l to within safe limits and to retard such movement as the booms approach said limits. The remainder of the system, now to be described, serves, on the other hand, to retard movement of the booms as they approach limits determined by the stroke of the hydraulic actuating cylinders.

As the second boom is raised link 25, rod 27 and arm 28 move to the right. After a period of such movement the abutment 29 near the base of the arm 28 abuts arm 35 moving the latter, together with arm 36, to the right with continued movement of the arm 28. Assuming the second boom is permitted by stop C to reach its normal limit of elevation, determined by the stroke of the cylinder 20a, as the boom approaches this condition, the stop E on rod 38 contacts control lever 51, gradually moving same towards its central position, thus elevation of the boom is retarded and finally arrested. When this condition is relieved by lowering of the second boom, and abutment 29 eventually moves away from arm 35, the latter, together with arm 36, is caused to return to the position shown in FIGS. 3 and 4 by one of the pairs of springs 42.

As the first boom 10 is raised the lower levelling rod 14 is moved to the left until the boom approaches its normal limit of elevation determined by the stroke of the actuating cylinder, whereupon stop Y on levelling rod 14 contacts arm 39, moving same to the left, thus stop H contacts control lever 50 and gradually moves same towards its central position, which serves to retard and finally arrest elevation of the first boom. When this position is relieved by lowering the first boom, stop Y releases arm 39, which together with arm 40, is returned to its original position by the other pair of springs 42.

If the first boom is lowered towards its stowed position on the vehicle, as it approaches this position stop X contacts and moves arm 39 so that the action of stop G slows down and finally arrests movement of the first boom by contacting control lever 50 and moving same gradually to its central position.

If the second boom is lowered towards its stowed position in superimposed relationship with the first boom on the vehicle, as it approaches this position the abutment 29a contacts arm 35 moving same to the left in FIGS. 3 and 4. Thus, the stop F on rod 38 contacts control lever 51 and gradually moves same to its central position which serves to retard and finally arrest movement of the second boom.

The assembly illustrated in FIGS. 3 and 4 is housed within a casing 45 on the first boom 10, which also houses the control levers 50 and 51 which are manually operable, duplicate controls being provided in the cage 13. Operation of the duplicate controls causes actual movement of the main control levers 50 and 51, which therefore ensures that the safety system operates when the boom structure is moved by an operator, whether in the cage or at the base. In some cases, an over-ride feature is provided which enables cancellation of the ability to control movement of the booms from the cage. However, the safety system is linked to the base controls and therefore remains operative at all times.

It is not intended to limit the invention to the above example only, many variations, such as might readily occur to one skilled in the art, being possible without departing from the scope of the invention.

Furthermore, in the arrangement described in relation to the drawings, movements of the second boom may be transmitted from the boom itself or any part or parts which move with the boom. However, it is preferable to utilise the rod 22 for this purpose as it moves through a smaller angle than the second boom, although its movement remains proportional to that of the latter. This smaller angle of movement is approximately equal to that moved by the first boom, so that both ends of the common link move through a similar angle, thus avoiding a complex construction of the link in order to combine the movements transmitted from both booms.

What is claimed is:

1. Access equipment comprising an articulated boom structure comprising a first boom pivotally mounted at one end on a vehicle or like supporting structure and at least a second boom pivotally connected to the free end of said first boom, hydraulic actuating cylinders connected for effecting pivoting movement of the second boom relative to the first boom and both booms relative to said supporting structure, control valves for said cylinders, movably mounted stops for controlling actuation of said valves, and means associated with each of said booms and movable therewith for transmitting movements thereof individually and collectively to said stops to actuate said control valves, said stops being so arranged that in response to movements of said booms and in accordance with permitted degrees of pivotal movement thereof operation of said actuating cylinders is controlled as appropriate to prevent the boom structure assuming a potentially unstable configuration.

2. Access equipment according to claim 1, wherein said means comprise a pair of members each reciprocable substantially linearly in response to clockwise and anti-clockwise pivoting movements respectively of its associated boom, said stops being carried by a further member also movable substantially linearly and operatively connected to said pair of members, the position of said further member being at all times representative of the combined linear positions of said pair of members.

3. Access equipment according to claim 2, wherein the members of said pair are adapted for relative movement in opposite directions upon simultaneous raising or lowering of both of said booms, said further member being pivotally connected to a common member extending between and pivotally connected to said pair of members, such that movements of said further member are at all times representative of the sum of the movements of said pair of members.

4. Access equipment according to claim 1, wherein said means are so movable with said booms that movements thereof are transmitted to further stops which are movable to actuate said control valves, said further stops being so disposed that operation of each actuating cylinder is gradually retarded as its respective boom approaches a fully lowered or fully elevated condition.

5. Access equipment according to claim 4, wherein said further stops are carried by two further linearly reciprocable members, each normally maintained in a non-operative position and movable only when its associated boom approaches a fully lowered or elevated position.

6. Access equipment according to claim 5, wherein one of said members is thus moved by a pair of spaced abutments attached to the means associated with one of said booms.

7. Access equipment according to claim 5, wherein one of said members is thus moved by a pair of spaced abutments mounted on a pivotable arm connected to the means associated with one of said booms.

8. Access equipment according to claim 1, wherein the means associated with said first boom is constituted by a levelling rod forming part of a parallelogram levelling linkage of which the other part is constituted by said first boom.

9. Access equipment according to claim 1, wherein the means associated with said second boom is constituted by a rod connected via a linkage to the ram of the hydraulic actuating cylinder for said second boom.

10. Access equipment according to claim 1, wherein said means, said stops and said control valves are all disposed on said first boom adjacent the lowermost end thereof.

11. Access equipment according to claim 10, wherein said control valves are manually operable and connected for simultaneous operation to duplicate control valves provided on a cage or working platform at the uppermost end of the boom structure.

j i l l UNITED STATES PATENT AND TRADEMARK OFFICE QE EQ'HGN 'HICATE P CO PATENT NO. 3,891,056

DATED June 24, 1975 INVENTOR(S) I DENIS HENRY ASHWORTH It is certified that error appears in the aboveidentified patent and that said Letters Patent are hereby corrected as shown below:

Column 6, after claim 11, the last claim was omitted.

Insert the last claim to read as follows:

l2. Access equipment as defined in claim 1 wherein said first boom is pivotally mounted on a turntable on said supporting structure.-

this

S irred and RUTH C. MASON Arresting Officer C. MARSHALL DANN (mnmissiuncr uflaltnls and Trademarks