US2500879A - Fluid-operated hoist - Google Patents

Description

March 14, 1950 c. D. P. SMALLPEICE 254M FLUID-OPERATED HOI'ST Filed Oct. 27, 1948 2 Shets-Sheet 1 I Invenfor CUfiBYQ PSMAZLPf/CE y ma wwg C. D. P. SMALLPEICE FLUID-OPERATED HOIST 2 SheetsQSheet 2 Filed Oct. 27, 1948 Inventor C0559 D. 5M/lllpf/C'f Attornejj Patented Mar. 14, 1950 UNITED STATES OFFICE FLUID-OPERATED HQIST Cosby D. P. Smallpeice, Swanwick Shore, Southampton, England 6 Claims. 1

This invention relates to a fluid-operated hoist (e. g., to a hoist-and this term is used in a generic sense-to be operated by compressed air, steam. or hydraulic pressure), and is an improvement in or modification of that disclosed in my United States patent specification No. 663,729, filed April 20, 1946.

This prior specification describes a hoist including a cylinder, a fluid-pressure-responsive piston reciprocable in one end of the cylinder and carrying a piston rod the free end of which is guided in the other end of the cylinder and carries a pulley or pulley set, a stationary pulley or pulley set within the cylinder beyond the limit of the piston travel, a hoisting cable having one end anchored and the other end extending through an opening in the cylinder after passing round the two pulleys or pulley sets, and controllable means for supplying operating fiuid to the end of the cylinder remote from that in which the movable pulley or pulley set is guided.

My main object is to provide an improved hoist of this kind with which the speed of lowering the load can, if desired, be increased, or the speed of lifting, particularly in the case of a light load, can be restricted.

According to the invention, a hoisting apparatus includes substantially similar coaxial cylinder portions, with the remote ends closed, separated by a portion carrying a stationary pulley set, a movable pulley set within one cylinder portion, a hoisting cable, passing round the pulley sets, having one end anchored and a hanging portion extending from between the cylinder portions, fiuid-pressure-responsive plungers, with the pulley sets between them, respectively reciprocable in the cylinder portions and interconnected for movement in unison, the movable pulley set being fast with the adjacent plunger, and controllable means for selectively supplying fiuid under pressure to the remote ends of the cylinder portions and for regulating the discharge of fluid from the said remote ends.

In addition, I may combine with either or with both of thesaid remote ends, or with the con trollable means, a valve which is normally open to a slight degree and which is adapted to be closed to a material extent when subjected to a substantial pressure rise, thus to provide only a leakage path, as when the fluid pressure is applied to the associated end to force the adjacent plunger outwardly therefrom.

In the accompanying drawings-- Figure 1 is a plan of a hoisting apparatus, ac-

cording to the invention, with various portions shown broken away.

Figures 2 and 3 are fragmentary cross-sections,

taken on the lines 22 and 33 of Figure 1, respectively.

Figure 4 is an enlarged view of the automatic valve shown on the right hand end of Figure 1; and

Figure 5 is a perspective view of the apparatus with parts cut away.

In order not to confuse the drawings the hoisting cable has been omitted from Figures 1, 2 and 3.

In carrying out the invention, there are two cylinder portions, A and B, which are spaced from one another by a block ll carrying a stationary pulley set 20, 20. As shown, the two cylinder portions include individual cylinders l2, 13, the adjacent ends of which abut the block I I. The remote ends of the cylinder portions are closed by plates l5, 16 held in position by tie rods H, I! and nuts I8, ill, the tie rods also serving for locating the adjacent ends of the cylinder portions against the block H.

The stationary pulley set comprises an appropriate number of pulleys 2U, 20 each mounted through a ball bearing 2|, 2! upon a common spindle 22 carried by a block I l, to which latter is secured a bolt 23 with a supporting eye whereby the hoisting apparatus can be suspended in a substantially horizontal position.

In a rather similar manner a movable pulley set comprises a number of pulleys 25, 25 each mounted through ball bearings upon a common spindle 26 carried by a block 21 which is slidable within the cylinder portion B. The right-hand end (Figure 1) of the block 2'! serves as a fluidpressure-responsive plunger, for which purpose it is shown as being fitted with a fieigible sealing ring 28 acting upon the wall of the cylinder portion B in a manner known per se.

The hanging portion 30 (Figure 5) of a hoisting cable passes through an opening 3| in the stationary block H and then over the adjacent end pulley 20, thence to a corresponding pulley 25 in the movable set, then back to the next pulley in the stationary set, and so on, until. finally the cable is anchored. With an equal number of pulleys in each set the cable may be anchored to a pin 33 carried by the stationary block II. If there is one more pulley in the stationary set than in the movable set the cable will preferably be carried forward again to the movable block 2'! to be anchored thereto in a corresponding manner.

Disposed in the cylinder portion A is a plunger 3 35 fitted, again in a known manner, with a sealing ring 36.

The plunger 35 and block plunger 2i are rigidly interconnected for movement in unison by spaced piston rods 37, 31 which pass outside the stationary pulley set through openings 38 provided for the purpose in the stationary block H, as indicated by Figure 2.

It will be understood that when fluid under pressure is admitted to the left-hand end of the cylinder portion A the plunger 35 will be driven to the right, carrying with it the movable set of pulleys 25, 25 and thereby raising the hanging end of the hoisting cable and any load thereon. During this action air in the cylinder portion B escaped through an automatic valve 39 which is shown as being provided in the end wall H3. This automatic valve is biassed to a position (see Figure 4) in which it is open only to a slight degree by means of a spring 40.

In the event, however, that fluid pressure should be admitted to the left-hand end of the cylinder portion A at a time when there is no load on the hoisting cable, the hanging end of the latter will tend to be raised very quickly,

and it is the purpose of the automatic valve 39 to prevent the poss bility of damage or shock occurring in these conditions. In the said conditions the pressure rise in the cylinder portion B serves for operating the valve disc #2 in the closing direction, the pressure diiierences thereon maintaining it in this position. The valve does not close completely, however, the disc 42 being provided with a washer 43 which will prevent the disc 42 from providing a complete seal, this leak being suflicient to allow the operation of the hoisting apparatus in the lifting direction when no load is being lifted.

Whilst the manner in which fluid pressure can be supplied to either of the remote ends of the cylinder portions A or B forms no part of the present invention, the drawings show two flexible pipe lines t5, t6 interconnecting each end and a trigger valve 47 (Figure to which is connected a pipe 48 for the supply of fluid under pressure. The trigger valve has two operating members 49, 5B, Depression to one of these members serves for supplying fluid pressure to the appropriate end of the selected cylinder portion,

and depression of the other serves for connecting this end to exhaust.

By making provision for the supply of fluid pressure to the right-hand end of the cylinder portion B it is possible to accelerate the lowering of the hanging end of the hoisting cable in those cases when there is no load on the cable, the sudden pressure rise in the cylinder portion B serving for closing the automatic valve 39, except for the small leak, in the manner described above.

In some cases also it may be, advisable to provide the cylinder portion A with an automatic valve, as indicated at 52, which is similar in all respects to the valve, 39. When lowering a load by the application of fluid pressure tothe cylinder portion B the automatic valve 52 will close, except for the aforesaid leak if the lowering shouldv be effected at a speed which is too great.

Naturally, when raising a load the fluid pressure applied to the cylinder portionv A will close the automatic valve 52 in the manner described in connection with the automatic valve 39.

What I claim as my invention and desire to secure by Letters Patent of theUnited States is:

1. Hoisting apparatu including substantially similar coaxial cylinders arranged end-to-end and with the remote ends closed, said cylinders separated by a portion carrying a stationary pulley set, a movable pulley set guided within one cylinder, a hoisting cable, passing round the pulley sets, having one end anchored and having a hanging portion extending from between the cylinders, a fluid-pressure-responsive plunger reciprocabe in the other cylinder and interconnected with the movable pulley set for movement in unison, and controllable means for supplying fluid under pressure to the appropriate end of the cylinder in which said plunger works to actuate said plunger.

2. Hoisting apparatus including substantially similar coaxial cylinders arranged end-to-end and with the remote ends closed, said cylinders separated by a portion carrying a stationary pulley set, a movable pulley set within one cylinder, a hoisting cable, passing round the pulley sets, having one end anchored and having a hanging portion extending from between the cylinders, fluid-pressure-responsive plungers, with the pulley sets between them, respectively reciprocable in the cylinders and interconnected for movement in unison, the movable pulley set being fast with the adjacent plunger, and controllable means for selectively supplying fluid under pressure to the remote ends of the cylinders and for regulating the discharge of fluid from said remote ends.

3. Hoisting apparatus including substantially similar coaxial cylinder portions arranged endto-end and with the remote ends closed, a stationary pulley set mounted substantially centrally within said cylinder portions, a movable pulley set within one cylinder portion, a hoisting cable, passing round the pulley sets, having one end anchored and having a hanging portion extending to the outside of said cylinder portions, fluidpressure-responsive plungers, with the pulley sets between them, respectivel reciprocable in said cylinder portions and interconnected for movcment in unison, the movable pulley set being fast with the adjacent plunger, and controllable means for selectively supplying fluid under pressure to the remote ends of the cylinder portions and for regulating the discharge of fluid from said remote ends.

4, Hoisting apparatus including substantially similar coaxial cylinder portions arranged end-toend and with the remote ends closed, a stationary pulley set mounted substantially centrally within said cylinder portions, a movable pulley set within one cyl'nder portion, a hoisting cable, passing round the pulley sets, having one end anchored and having a hanging portion extending to the outside of said cylinder portions, fluid-pressureresponsive plungers, with the pulley sets between them, respectively reciprocable in said cylinder portions and interconnected for movement in unison, the movable pulley set being last with the adjacent plunger, controllable means for selectively supplying fluid under. pressure to the remote ends of the cylinder portions, and automatic valves for regulating thev discharge of fluid from the said remote ends, said valves being normally open to a small degree and adapted to close to a material extent when subjected to a substantial pressure rise.

5. Hoisting apparatus, according to claim 1, and in which the closed end of the cylinder in which the movable pulley set works is provided with a normally-open. automatic valve adapted nearly to close when subjected to a substantial pressure rise.

6. Hoisting apparatus including substantially similar coaxial cylinders arranged end-to-end and, with the remote ends closed, said cylinders separated by a block carrying a stationary pulley set, plates closing the remote ends of said cylinders, said plates, cylinders and block all bolted together, a movable pulley set within one cylinder, a hoisting cable, passing round the pulley sets, having one end anchored and having a hanging portion extending from between said block, fluidpressure-responsive plungers, with the pulley sets between them, respectively reciprocable in said cylinders and interconnected for movement in unison, the movable pulley set being fast with the adjacent plunger, and controllable means for selectively supplying fluid under pressure through said plates and for regulating the discharge of fluid from said plates.

COSBY D. P. SMALLPEICE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 981,268 Hurd Jan. 10 1911 1,188,760 Hagenbucher June 2'7, 1916

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