US3344890A

US3344890A - Lifting arrangement

Info

Publication number: US3344890A
Application number: US591898A
Authority: US
Inventors: Loef Jakob
Original assignee: Steinbock GmbH
Current assignee: Steinbock GmbH
Priority date: 1966-05-06
Filing date: 1966-11-03
Publication date: 1967-10-03
Anticipated expiration: 1984-10-03
Also published as: FR1513611A; DE1456892A1; DE1456892C3; DE1456896A1; DE1456896B2; DE1456896C3; GB1135814A; DE1456892B2

Description

Oct. 3, 1967 J. L OEF I 3,344,890

LIFTING ARRANGEMENT Filed Nov. 3, 1966 8 Sheets-Sheet 1 /6 I /0 I IF l :il W1 9 1;

i 1 I W INVENTOR.

JAKOB LOEF BY m) M Euwm AGENTS Oct. 3, 1967 J, LOE 3,344,890

LIFTING ARRANGEMENT Filed Nov. 5, 1966 s Sheets-Sheet 2v INVENTOR. JAKOB LOEF BY 730w WJ AGENTS J. LOEF LIFTING ARRANGEMENT Oct. 13,1967

Filed Nov. 3, 1966 INVENTOR.

JAKOB LOEF BY 73M M gum AGENTS Oct. 3, 1967 J LOEF LIFT ING ARRANGEMENT Filed Nov. 5, 1966 8 Sheets$heet 4 INVENTOR. JAKOB LOEF AGENTS 8 Sheets-Sheet 5 INVENTOR. .JAKOB LOEF A NTS Oct. 3, 1967 J LQEF LIFTING ARRANGEMENT Filed Nov. 5, 1966 WW 3W Oct. 3, 1967 J. LOEF- 3,344,390

LIFTING ARRANGEMENT Filed Nov. 3, 1966 Sheets-Sheet 6 'INVENTOR. JAKOB LOEF BY 25M M 255W AGENTS Oct. 3, 1967 J. LOEF LIFTING ARRANGEMENT 8 Sheets sheet 7 Filed Nov. 5, 1966 INVENTOR. JAKOB LOEF BY Q2; 4M1

AGENTS Oct. 3, 1967 J. LOEF 3,344,890

LIFTING ARRANGEMENT Filed Nov. 5, 1966 8 Sheets-Sheet 8 .FJ'gJ4 9 f? i 13 I ii 3 i'! i I I INVENTOR. JAKOB LOEF id MW AGENTS United States Patent 3,344,890 LIFTING ARRANGEMENT Jakob Loef, Moosburg, Germany, assignor to Steinbeck G.m.b.H., Moosburg, Germany Filed Nov. 3, 1966, Ser. No. 591,898 Claims priority, application Germany, May 6, 1966, St 25,357; June 20, 1966, St 25,551 Claims. (Cl. 187-9) This invention relates to lifting arrangements, and particularly to a lifting arrangement for a fork truck or like vehicle equipped with a telescopic column or mastwhich permits a load carrier, such as a fork, to be lifted above the normal height of the vehicle.

More specifically, the invention is concerned with a lifting arrangement in which hydraulic power is used for telescopically moving the portions of the column between positions of maximum and minimum length, and for moving the load carrier along the column in an upright path.

A primary object of the invention is the provision of a pressure-fluid operated lifting arrangement in which tension members connect the hydraulic motor to the several portions of the column and to the load carrier, and in which the combined length of the tension members is as small as possible.

The tension members, such as chains, ropes, or cables are subject to wear, and need to be replaced from time to time. A reduction in the length of the tension members significantly reduces the maintenance cost of the lifting arrangement.

Yet another object is the provision of a minimum number of guide pulleys or their equivalents over which the tension members are trained, the rate of wear of the tension members being a direct function of this number.

A further object is the provision of a unitary hydraulic motor for moving the several portions of the column relative to each other and for moving the load carrier relative .to the column, the motor being supported directly on the vehicle frame so that the motor does not have to be lifted with a movable column portion or with the load carrier.

An additional object is the provision of a lifting arrangement in which the hydraulic motor, if interposed between the operator of the vehicle and the load carrier, is not in the normal field of view of the operator when the column is at its minimum height, and does not significantly interfere with inspection of the load carrier by the operator in other positions of the lifting arrangement. More specifically, the invention aims at providing a hydraulic motor whose cylinder and plunger move vertically relative to each other, and whose overall axial dimension in the retracted position of the plunger is not significantly greater than one half of the minimum length of the column.

With these and other objects in view, the invention in one of its aspects resides in a lifting arrangement includ ing an elongated column of telescopically variable height, a bottom portion of the column being fastened to the vehicle frame for support, and the top portion being guided on the bottom portion. A load carrier is arranged for movement along the column, and a single, pressure-fluid operated motor mounted on the support causes relative movement of the column portions and of the load carrier. The motor has a cylinder and a plunger of which one, preferably the cylinder, is attached to the support so that the other one, preferably the plunger, moves upwardly away from the cylinder during the axial expansion of the motor and downward toward the cylinder during the contraction of the motor.

Three pulleys and two flexible tension members transmit motion from the plunger to the top portion of the column and to the load carrier. The first tension member is trained over a first pulley rotatably mounted on the plunger, and its ends are fastened respectively to the column portions in such a manner that the end portions are at least in part downwardly spaced from the first pulley. The second tension member is trained over a second pulley high on the top portion of the column and a third pulley on the plunger. One of its ends is attached to the load carrier, and the other end is fastened either to the top portion of the column or the plunger in such a manner that the load carrier moves upward when the plunger is retracted into the cylinder and third pulley moves with the plunger.

The exact nature of this invention as well as other objects and features thereof will be readily apparent from consideration of the following detailed description of preferred embodiments relating to the annexed drawing in which:

FIG. 1 shows as much of a fork lift truck as is needed for an understanding of the invention, the view being in side-elevation and partly in section;

FIGS. 2 and 3 show the apparatus of FIG. 1 in different operating positions in corresponding views;

FIGS. 4 and 4a jointly show the apparatus of FIG. 1 together with its hydraulic circuit, further portions of the apparatus being broken away to reveal internal structure;

FIGS. 5 to 7 illustrate a portion of the hydraulic circuit of FIG. 4a in different respective operating positions;

FIGS. 8 to 10 show a modified embodiment of the invention in views respectively corresponding to those of FIGS. 1, 3, and 2;

FIG. 11 shows a portion of the apparatus of FIG. 8 in front elevation and partly in section;

FIGS. 12 and 13 show a third embodiment of the invention in views corresponding to those of FIGS. 1 and 3; and

FIG. 14 shows a portion of the device of FIG. 13 in front elevation.

Referring now to the drawing in detail, and initially to FIGS. 1 to 7, there is shown the telescoping column of a fork lift truck. The cylindrical tubular bottom portion of the column is fixedly attached to the front end of the truck body 51 in the usual manner. The coaxial tubular top portion 2 of the column is guided in the bottom portion 1 for vertical movement. An upright stationary cylinder 3 is fixedly mounted in the bottom portion 1, and a hollow cylindrical plunger 4 is coaxially received in the stationary cylinder 3 for vertical movement inward and outward of the open top of the latter.

As is best seen in FIG. 4, the plunger 4 is hollow and downwardly open toward the stationary cylinder 3. A piston 6 divides the cavity of the plunger 4 into two compartments. A piston rod 5 extends upwardly through a packing 17 in the otherwise closed top of the plunger 4 and carries a U-shaped bracket 7 which rotatably support a pulley 8. Two similar pulleys 9 are mounted on the topmost portion of the plunger 4 for rotation about a common horizontal axis. Yet another pulley it) is mounted at the upper end of the top column part 2.

A chain 11 is trained from a fastener 16 near the upper end of the column portion 2 over the pulley 8 on the piston rod 5 and the pulley 10 to a fastener 15 of the load lifting fork 50. The fork is guided vertically on a frame which is fixedly fastened to the top portion 2 of the column in a manner not shown since it is entirely conventional. A pair of chains 12 are trained over the pulleys 9 respectively from fasteners 13 in the bottom part 1 of the column slightly below the upper end of the stationary cylinder 3 to fasteners 14 at the lower end of the column portion 2. The bottom portion 1 of the column is downwardly closed, and a cover (not shown) is normally provided on the top portion 2 to close the column except for an aperture which accommodates the pulley 10.

Connecting

nipples

13, 19 at the closed top end of the plunger4 and at the closed lower end of the cylinder 3 permit hydraulic fluid to be admitted to and withdrawn from the cylinder and the plunger compartment above the piston 6. A flexible pressure hose 26 connected to the nipple 18 is wound on a reel 21 rotatably attached to the bottom portion 1 of the column. The reel is equipped with a non-illustrated spring which tends to turn the reel 21 counterclockwise, as viewed in FIG. 4, and thereby wind the hose 29 on the reel. The nipple 18 travels in non-illustrated vertical slots of the

column portions

1, 2 when the apparatus moves between the positions illustrated in FIGS. 1, 2, and 3. The hose 20 is connected to a hollow trunnion of the reel 21 in a conventional manner.

Pipes

22, 23 lead from the trunnion on the reel 21 and from the nipple 19 to a rotary control valve 28 which is operated by means of a radial arm 25. The rotary member 24 of the valve 28 has two circumferentially spaced

recesses

26, 27 in its otherwise cylindrical face. The recesses may be aligned with openings in the valve housing which communicate respectively with the

pipes

22, 23, with

extensions

29, 30 of the

pipes

23, 22, with a return line 31, and with the discharge pipe 34 of a motor driven pump 33. The return line 31 has an open end in a sump 32 in which the suction pipe of the pump 33 is partly immersed.

The afore-described telescopic column is hydraulically operated by means of the Valve 28 in the following manner 1 Let it be assumed that the apparatus is initially in the position shown in FIG. 3 in which the upper column portion 2 is fully retracted into the bottom portion 1, the piston 6 is in its upmost position, the plunger 4 is retracted into the cylinder 3 and the fork 50 rests on the ground. The valve 28 is brought into the position shown in FIG. 7, and the pump 33 is started.

Hydraulic fluid is pumped from the sump 32 through the discharge pipe 34, the recess 27, the extension 30, the pipe 22, and the hose 20 into the plunger compartment above the piston 6 while the cylinder 3 and the communication compartment of the plunger 4 under the piston 6 are vented to the sump 32 through the pipe 23, the recess 26 of the valve 28, and the return line 31 which is equipped with a non-illustrated check valve. The piston rod is retracted by the pressure fluid into the plunger 4, and the fork 50 is raised until the position of FIG. 2 is reached. A limit switch in the circuit of the pump motor and a check valve (not shown) in the pipe 34 may be employed in a conventional manner to limit the inward movement of the piston rod 5.

The valve 28 is next slowly shifted to the position shown in FIG. 6 in which both

pipes

22, 23 are connected to the pump discharge pipe 34 by the

extensions

29, 30 and the valve recess 27. The plunger 4 is expelled from the cylinder 3. Because the effective area of the piston 6 is smaller on the annular top face of the piston than on the circular bottom face, the piston rod 5 moves outward of the plunger 4. The rate of fluid flow from the recess 27 to the extension 29 can be throttled by suitably positioning the rotary valve member 24 so that the outward movement of the piston 6 and the piston rod 5 is never faster than the movement of the plunger 4, whereby the fork 50 moves continuously upward until the position of FIGS. 1 or 4 is reached in which the column is extended to its greatest length, and the fork 50 arrives at the highest point to which it can be lifted.

When the fork 50 is to be lowered, the valve 28 may be shifted to a non-illustrated position intermediate the positions of FIGS. 5 and 6 in which the recess 27 connects the pipe 23 with the return line 31 whereas the pipe 22 and the corresponding extension 30 are blocked. Pressure fluid is thereby released from the cylinder 3 for return to the condition of FIG. 3. It is also possible to shift the valve into the position illustrated in FIG. 5 for lowering the fork 50 whose weight keeps the piston rod 5 in its projecting position.

The apparatus may be blocked in the position of FIGS. 1 and 4 by shifting the valve 28 to the position shown in FIG. 4a in which the

pipes

22, 23 are connected by the recess 26, and the pump output is directly returned to the sump 32.

The fork 5t) and the hydraulic control circuit have been shown in FIG. 4 on the same side of the

column

1, 2 for the convenience of pictorial representation. It will be understood that they are actually offset relative to the column axis to prevent interference of the control circuit with the necessary vertical movement of the fork 50.

The modified apparatus of the invention shown in FIGS. 8 to 11 has a stationary cylinder 3 in which a hollow plunger 4 is vertically movable. The lower end of the plunger 4 is closed by a bottom plate 36 as is best seen in FIG. 11. A cylindrical plunger rod 5' is coaxially slidable inthe top wall of the plunger 4' so that the end face 6' of the rod 5 may be moved inward of the plunger 4' from the position seen in FIG. 11. A horizontal cross bar 7 on the upper end of the rod 5 carries two freely rotatable pulleys 8. A shaft 37 on the uppermost portion of the plunger 4' carries two coaxial pairs of

pulleys

9, 35.

As shown in FIGS. 8 to 10, the cylinder 3, plunger 4', and rod 5 are arranged coaxially in a tubular column mainly consisting of a bottom portion 1 and a top portion 2 equipped with

fasteners

13, 14 and a pulley 10 as described with reference to FIGS. 1 to 7. A load lifting fork 50 is guided on a non-illustrated frame and is suspended by fasteners 15 from two chains 11 trained in sequence over two coaxial pulleys 10 of which only one is visible in the drawing, the pulleys 9 on the plunger 4' and the pulleys 8 on the cross bar 7'. The free ends of the chain 11 are fastened to the shaft 37.

Another pair of chains 12 extends between the

fasteners

13 and 14, and is trained over the pulleys 35 on the plunger 4'.

The cavities within the cylinder 3 and the plunger 4' are connected to a pump and to a sump by means of a control valve arrangement similar to that shown in FIGS. 4a to 7 which permits pressure fluid to be admitted to the cavities and withdrawn to a sump through

nipples

18, 19.

The apparatus shown in FIGS. 8 to 11 is operated as follows:

Starting from the position of FIG. 9 in which the rod 5 is retracted into the plunger 4, the latter is retracted into the cylinder 3, the column is reduced to its smallest height, and the fork 50 rests on the ground, pressure fluid is admit-ted to the cavity of the plunger 4' to expel the rod 5'. The fork 50 is thereby raised by twice the stroke of the rod 5 to the position shown in FIG. 10. Pressure fluid is thereafter admitted to the cylinder 3, and the plunger 4' is raised where-by the top portion 2 of the column is lifted by the chain 11. Pressure fluid is simultaneously released from the cavity of the plunger 4' so that the cross bar 7' and the pulleys 8 mounted thereon move by one half of the stroke of the plunger 4' relative to the top portion 2 of the column from the position indicated by broken lines in FIG. 8 to the fully drawn position in which the fork 50 reaches the highest level above ground.

The available displacement of the fork 50 in the apparatus of FIGS. 1 to 7 is twice the combined strokes of the hollow plunger 4 and of the piston 6. In the embodiment of the invention illustrated in FIGS. 8 to 11, the hydraulic apparatus is capable of lifting the fork 50 a distance equal to the sum of twice the stroke of the plunger 4' plus three times the stroke of the rod 5. The difference in available lifting height between the two hydraulic devices is due to the fact that the chain 11 travels over two reversing pulleys in FIGS. 1 to 7 and over three pulleys in FIGS. 8 to 11.

In the modified embodiment of the invention shown in FIGS. 12 to 14, the telescoping bottom and

top portions

1, 2 of a column are axially moved relative to each other by a hydraulic lifting arrangement which differs from that shown in FIGS. 1 to 7 mainly by the absence of the piston 6 and piston rod 5 and by the provision of a solid plunger 4 having three

coaxial pulleys

8', 9, and 9 mounted thereon.

A cable 11' whose ends are attached to a fastener 15 on the fork 50 and to a fastener 16' in the axially central part of the column portion 2 is trained over a pulley near the top of the column portion 2 and the pulley 8' on the plunger 4". Two cables 12' are attached to respective fasteners 13 on the column portion 1 and fasteners 14 at the lower end of the column portion 2. The position of the fastener 16 is higher than that of the pulley 8 in all operative positions of the apparatus.

The hydraulic control circuit for the apparatus of FIGS. 12 to 14 consists essentially of a non-illustrated three-way valve which permits the cavity of the cylinder 3 to be blocked or to be connected with a pump or with a return line for movement of the apparatus between the positions of FIGS. 12 and 13. The valve may be of the rotary type shown in FIGS. 4a to 7.

It is a common feature of the several embodiments of the invention described hereinabove, that the hydraulic motor constituted by the cylinder 3 together with the plunger 4 and the piston rod 5, by the cylinder 3 together with the plunger 4 and the rod 5', and by the cylinder 3 together with the plunger 4" has an axial length when in the retracted condition which is not significantly greater than one half of the axial length of the top portion 2 of the column which is equal to the minimum length of the column.

The combined length of the tension members emloyed, such as chains and cables, is relatively small, and is particularly small in the embodiment of the invention described with reference to FIGS. 1 to 7. The tension members are subject to unavoidable wear and must be replaced from time to time. The savings achieved by the use of shorter tension members in the first-described embodiment as compared to the embodiment illustrated in FIGS. 12 to 14 more than balance the cost of the more complex structure of the first embodiment during the normal life of the apparatus. Even the apparatus shown in FIGS. 12 to 14, however, is fully effective with cables, ropes, or chains of a much smaller combined length than was possible in similar devices known heretofore.

While the column of the invention has been shown to consist of cylindrical tubes, it will be understood that the tubes may be replaced by two elongated, telescopically engaged lattice girders as is conventional in this art. Such girders have openings which permit the operator of the fork lift to view the fork and the material to be loaded thereon from a station behind the column. The relatively small height of the several hydraulic motors of the invention, even when the fork 50 is at its highest position leaves the operators field of view virtually unobstructed. Only the

slim rods

5, 5 may enter the field under the most unfavorable conditions. In the embodiment of the invention shown in FIGS. 8 to 11, the rod 5' moves downward and out of the operators field of view during the lifting operation.

The hydraulic motors are free of plungers, piston rods or the like which move outward of a pressure cylinder in a downward direction. The oil leaks due to gravity which are practically unavoidable where a packing extends downward toward the ambient atmosphere are thus safely avoided in the devices of this invention.

The hydraulic motors of the invention are readily controlled by a single valve unit as has been shown in FIGS. 4a to 7. The application of analogous valve systems to the second and third embodiments of the invention will be obvious to those skilled in the art. The hydraulic motors have each but a single cylinder member on which all other elements of the motor are arranged. The motors require a minimum of space. The hydraulic motors are subjected to axial stresses only. Forces having radial components cannot be transmitted to the motors by the flexible tension members which connect the motors with the fork 50 and with the movable top portion 2 of the column. The cylinder member is fixedly fastened to the supporting vehicle frame and carries the other element of the hydraulic motor. It transmits the weight of the other elements directly to the vehicle frame 51 which provides its support.

If so desired, the forks 50 of the devices of the invention shown in FIGS. 1 to 11 may be lifted over the full height of the top portion 2 of the column while the latter is retracted.

While the invention has been described with specific reference to fork lift trucks, it will be appreciated that other types of load carriers may be substituted for the fork 59 without affecting the mode of operation of the illustrated lifting arrangments of the invention.

Obviously many other modifications and variations of the present invention are possible in the light of the above.

teachings. It is therefore to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

What is claimed is:

1. A lifting arrangement for a fork truck and like vehicle comprising, in combination:

(a) a support;

(b) a column having a bottom portion and a top portion elongated in a common upright direction,

(1) said bottom portion being fixedly mounted on said support, and said top portion being guided on said bottom portion for longitudinal movement toward and away from said bottom portion,

(2) whereby the length of said column may be varied between a minimum and a maximum;

(c) a pressure-fluid operated motor including a cylinder member having an upright axis and defining a cavity therein, and a plunger member axially movable inward and outward of said cavity, whereby said motor axially contracts and expands during relative axial movement of said members,

(1) one of the members of said motor being fixedly mounted on said support, and the other member moving upwardly away from said one member during the expansion of said motor;

(d) first pulley means rotatably mounted on said other member;

(e) a first, elongated, flexible tension member trained over said first pulley means and having two end portions,

( 1) said end portions being respectively fastened to said bottom portion and to said top portion, and being at least in part downwardly spaced from said pulley means when said column is at said maximum length and at said minimum length thereof;

(f) second pulley means on said top portion upwardly spaced from said other member of the motor;

(g) third pulley means on said other member of said motor;

(h) a load carrier arranged for upright movement along said top member;

(i) a second, elongated, flexible tension member trained over said second and third pulley means, and having one end portion attached to said load carrier; and

(j) fastening means fastening the other end portion of said second tension member to one of said top portion and said other member for upward movement of said load carrier when said plunger member moves inward of said cylinder member.

2. An arrangement as set forth in claim 1, wherein said one member of said motor is said cylinder memher and said other member is said plunger member, the axial length of said motor in the contracted condition thereof being not substantially greater than one half of the minimum length of said column.

3. An arrangement as set forth in claim 2, further comprising a piston member, and a rod member, said plunger member defining therein another cavity, said piston member being axially movable in said other cavity in sealing engagement with the plunger member in such a manner that said other cavity is axially divided into two compartments, said rod member being fastened to said piston member and extending axially therefrom through one of said compartments and outward of said other cavity, one of said first and second pulley means being mounted on said rod portion, and the other one of said first and second pulley means being mounted directly on said plunger member.

4. An'arrangement as set forth in claim 3, further comprising a source of pressure fluid, and valve means for admitting said pressure fluid to the cavity of said cylinder member and to said one compartment, and for releasing the fluid from said cylinder cavity and from said one compartment.

5. An arrangement as set forth in claim 4, wherein the other one of said compartments freely communicates with said cavity of the cylinder member, said first pulley means being mounted for rotation about a fixed axis on said plunger member and said third pulley means being mounted on said rod portion for rotation about an axis fixed with respect to the rod portion outside the cavity of said cylinder member, said fastening means fastening said other end portion of said second tension member to said top portion.

'6. An arrangement as set forth in claim 5, wherein said valve means include means for sequentially admitting said pressure fluid to said one compartment and to said cylinder member.

7. An arrangement as set forth in claim 5, wherein said valve means include means for admitting said pressure fluid first to said one compartment and for thereafter admitting said pressure fluid to the cavity of said cylinder member at a throttled rate.

8. An arrangement as set forth in claim 2, further comprising .a source of pressure fluid; valve means; and a rod member,

(1) said plunger member being formed with another, substantially closed cavity therein, and said rod member being axially movable inward and outward of said cavity,

(2) said valve means connecting said source to said cavities for admitting said fluid to said cavities, and for withdrawing said fluid from the cavities,

(3) said first pulley means being secured to said plunger member for rotation about an axis fixed relative to said plunger member, and said third pulley means being mounted on said rod member for rotation about an axis fixed with respect to said rod member,

(4) said fastening means fastening said other end portion of said tension member to said plunger memher.

9. An arrangement as set forth in claim 2, wherein said bottom portion and said top portion are hollow, one of said portions being telescopically received in the other portion, and said motor being received in said one portion when said column is at the minimum length thereof.

10. An arrangement as set forth in claim 2, wherein said first and third pulley means are mounted on said plunger member for rotation about respective axes fixed on said pulley member.

References Cited UNITED STATES PATENTS 3/1959 Gunning l 879 2/1963 Ramsey 1879

Claims

1. A LIFTING ARRANGEMENT FOR A FORK TRUCK AND LIKE VEHICLE COMPRISING, IN COMBINATION: (A) A SUPPORT; (B) A COLUMN HAVING A BOTTOM PORTION AND A TOP PORTION ELONGATED IN A COMMON UPRIGHT DIRECTION, (1) SAID BOTTOM PORTION BEING FIXEDLY MOUNTED ON SAID SUPPORT, AND SAID TOP PORTION BEING GUIDED ON SAID BOTTOM PORTION FOR LONGITUDINAL MOVEMENT TOWARD AND AWAY FROM SAID BOTTOM PORTION, (2) WHEREBY THE LENGTH OF SAID COLUMN MAY BE VARIED BETWEEN A MINIMUM AND A MAXIMUM, (C) A PRESSURE-FLUID OPERATED MOTOR INCLUDING A CYLINDER MEMBER HAVING AN UPRIGHT AXIS AND DEFINING A CAVITY THEREIN, AND A PLUNGER MEMBER AXIALLY MOVABLE INWARD AND OUTWARD OF SAID CAVITY, WHEREBY SAID MOTOR AXIALLY CONTRACTS AND EXPANDS DURING RELATIVE AXIAL MOVEMENT OF SAID MEMBERS, (1) ONE OF THE MEMBERS OF SAID MOTOR BEING FIXEDLY MOUNTED ON SAID SUPPORT, AND THE OTHER MEMBER MOVING UPWARDLY AWAY FROM SAID ONE MEMBER DURING THE EXPANSION OF SID MOTOR; (D) FIRST PULLEY MEANS ROTATABLY MOUNTED ON SAID OTHER MEMBER; (E) A FIRST, ELONGATED, FLEXIBLE TENSION MEMBER TRAINED OVER SAID FRIST PULLEY MEANS AND HAVING TWO END PORTIONS, (1) SAID END PORTIONS BEING RESPECTIVELY FASTENED TO SAID BOTTOM PORTION AND TO SAID TOP PORTION, AND BEING AT LEAST IN PART DOWNWARDLY SPACED FROM SAID PULLEY MEANS WHEN SAID COLUMN IS AT SAID MAXIMUM LENGTH AND AT SAID MINIMUM LENGTH THEREOF; (F) SECOND PULLEY MEANS ON SAID TOP PORTION UPWARDLY SPACED FROM SAID OTHER MEMBER OF THE MOTOR; (G) THIRD PULLEY MEANS ON SAID OTHER MEMBER OF SAID MOTOR; (H) A LOAD CARRIER ARRANGED FOR UPRIGHT MOVEMENT ALONG SAID TOP MEMBER; (I) A SECOND, ELONGATED, FLEXIBLE TENSION MEMBER TRAINED OVER SAID SECOND AND THIRD PULLEY MEANS, AND HAVING ONE END PORTION ATTACHED TO SAID LOAD CARRIER; AND (J) FASTENING MEANS FASTENING THE OTHER END PORTION OF SAID SECOND TENSION MEMBER TO ONE OF SAID TOP PORTION AND SAID OTHER MEMBER FOR UPWARD MOVEMENT OF SAID LOAD CARRIER WHEN SAID PLUNGER MEMBER MOVES INWARD OF SAID CYLINDER MEMBER.