US1940823A - Hydraulic jack - Google Patents

Description

Bec. ze, 1933. B, H, SHINN 1,940,823

HYDRAULIC JACK Filed May 16, 1950 5 Sheets-Sheet 1 Dec. 26, y1933. B H sHlNN 1,940,823

HYDRAULIC JACK 16 3 Sheets-Sheet 2 Deen 26, 1933. a H, SHINN 1,940,823

HYDRAULIC JAC K Filed May 16, 1930 3 Sheets-Sheet 3 y gag!!! Patented Bec. 26, 1933 PTENT @FFICE HYDRAUUIC JACK Byron H. Shinn, Washington, la., assignor to Shinn Devices Corporation, Washington, Pa., a corporation of Delaware Application May 16, 1930. Serial No. 453,072

9 Claims.

This invention is a hydraulic jack, covering certain improvements and modifications over the hydraulic jack shown and claimed in my copending application Serial No. 375,534, filed July One of the important features of the jack is the pumping mechanism which operates the lifting arm of the jack rather quickly, to bring the lifting arm upwardly to connect with the load.

l The raising of the lifting arm into engagement with the load is, in effect, lost motion as far as actual lifting of the load is concerned, therefore the more quickly it can be performed the better. Accordingly, the jack is provided with a large l low pressure cylinder, and with a small high pressure cylinder, these cylinders containing pistons operated by common power applying mechanism. At the beginning of the operation, the large low pressure cylinder sends a large quantity of liquid into the power cylinder and raises it relatively quickly until it takes hold of the load. As thepumping operation continues, the pressure in the system builds up rapidly, due to the fact that the lifting arm has taken hold of the load. When the pressure reaches a certain predetermined point, pressure responsive two-way valve mechanism comes into play for shutting off the low pressure cylinder and for bringing the small high pressure cylinder into operation. The small cylinder, with its smaller diameter, gives a largely increased mechanical advantage, according to Well known principles of hydraulics.

The described change-over from the low pressure cylinder to the high pressure cylinder is entirely automatic as far as the operator is concerned. The operation is controlled by the pressure existing in the system. The operator pumps on the operating handle and if the pressure is low, as it'would be at no load or light 40 load, the lifting arm moves up rapidly because it is being operated by the large low pressure cylinder and piston. If `for any reason the load increases, as for example, would happen when the lifting arm takes hold of the axle of an automobile or motor truck, the pressure builds up rapidly, to a point such that the automatic two-way valve cuts out the low pressure cylinder and cuts in the high pressure cylinder, thereby changing the lifting power of the jack, and its mechanical advantage, without materially changing the force that the operator has to apply on the operating handle.

Another important feature of the invention is release mechanism for causing the jack to let go of the load, which release mechanism may be (Cl. 13S-9) operated from a plurality of points on the jack. One of these release points is preferably fairly close to the lifting arm of the jack, while another is preferably on the operating handle. By the presence of a release device near the lifting erm, the mechanic, While he is more or less underneath the car or underneath the axle, probably sitting on the floor, can cause the jack to lower the load partially or completely, without getting up and going to the far end of the jack to the operating handle. This feature is of real` practical importance, and a valuable time saver for the mechanic.

The release mechanism above described comprises a ratchet mechanism for holding the lifting arm in any given position. It also comprises a by-pass valve from the power cylinder back to the reservoir. In order to release the jack, the ratchet must be released-and the by-pass valve must be open. To this end, there is a rod or similar control mechanism extending longitudinally of the jack which is connected both to the ratchet and to the by-.pass valve, so that the ratchet and valve are simultaneously released. This operating rod can readily be controlled from any point along the jack simply by securing t0 the rod an operating handle at the desired point.

An important practical detail of the ratchet release is that the release on the operating handle requires a slight movement of the handle to effect the release. This slight movement gives a little extra pressure in the power cylinder which takes the load off the ratchet so that the tooth can be readily disengaged from the rack.

The lifting or power cylinder has a piston which is connected with the pusher arxn which in turn moves in a rectilinear path; the pusher arm is provided with an inclined cam face which pushes against an anti-friction roller on the under side of the power arm and raises it and at 4 the same time raises the lifting arm, the combination forming, in effect, a lever of the third class. The inclined cam face is supported on a bed plate, through the medium of anti-friction rollers, whichmay be carried either by the cam member or the bed plate but which preferably are carried by the bed plate.

The two pump cylinders are placed side by side in parallel relation; the piston rods for these cylinders move inparallel paths. Power is applied to the pistons by a common pumping or operating handle, which is connected to both piston rods by an equalizing mechanism. A lazy tongs equalizer may be used in this connection.

Another feature of the invention is a non-fouling caste so designed that it will clear itself of waste and debris which the ordinary caster tends to pick up.

Other advantages and novel features of construction and operation will now be described in connection with the accompanying drawings illustrating a preferred embodiment of the invention. It should be understood, however, that the invention is not to be limited to the precise mechanism here described, but may be carried out in other ways as falling Within the inventive concept.

In the accompanying drawings:-

Fig. 1 is a plan view of the jack.

Fig. 2 is a side view partly in section.

Fig. 3 is a section on the line 3-3 of Fig. 1.

Fig. 4 is a section, on an enlarged scale, of the valve mechanism, taken on the line 4-4 of Fig. 2.

Fig. 5 is a section through part of the valve mechanism taken on the line 5-5 of Fig. 1.

Fig. 6 is a. perspective view, on an enlarged scale, of a detail of part of the release mechanism.

Fig. 7 is a perspective view, on a smaller scale, of the operating handle and associated parts.

Fig. 8 is a sectional view of the non-fouling caster.

Fig. 9 is a side elevational view, partly in section of the caster as shown in Fig. 8;.

Fig. 10 is a detail plan view of the lost-motion connection for the bleeder valve;

Fig. 11 is an' elevation, partly in section, of the connection shown in Fig. 10, and

Fig. 12 is a detail view of a spring used in a valve mechanism as shown in Fig. 4.

Referring now to the accompanying drawings in which similar reference characters indicate similar parts, the jack is built on a long, low frame, comprising longitudinal extending side frame members 1 and 2, and end frame members 3 and 4, one end carrying the non-fouling caster 141 while the other end carries the two wheels 6. The pumping mechanism comprises a large low pressure cylinder 7, the piston of which is connected to the piston rod 8, the outer end of which reciprocates through a hole in a brace member 9.

Alongside the low pressure cylinder is a small high pressure cylinder 10,'the piston of which is `actuated by the piston rod 12, the outer end of which is guided through a suitable hole in member 9.

Power for operating the pump cylinders 7 and 10 comes from the operating handle 13, the lower end of which is provided with a' stirrup 14 which is pivoted to the frame on the axis 15. The lower end of the handle is provided with an extension 16, to which is pivoted, on the axis 17, a pair of links 18 which in turn are pivotally connected, on the axis 19, with a rod 20 which in turn is pivotally connected at 21 with a lazy tongs mechanism 22, the outer ends of which are pivoted to blocks 23 that are fixed to the piston rods 8 and 12.

The described mechanism enables piston rods 8 and 12 to move in strict rectilinear paths, while the force from the operating handle 13, delivered to the central part of the lazy tongs is distributed by the lazy tongs substantially equally to the two piston rods 8 and 12.

'Ihe valve mechanism will now be described. In this valve mechanism liquid from the two pump cylinders 7 and 10 is delivered to a common valve device, the valves being so arranged that when the pressure in the system is low, as would bethe case when the lifting arm is moving up to the load, the large cylinder 7 is doing the pumping, while when the pressure rises, due to the arm taking hold of the load, the small high pressure cylinder 10 comes into operation, thereby increasing the mechanical advantage of the jack. This change-over is automatically done by the pressure responsive valve mechanism which will now be described.

The valve housing, indicated generally at 30, is provided with a valve chamber 32, to the upper part of which oil or other iluid from the high pressure cylinder 10 is delivered through the conduit 33. To the lower part of the chamber 32 oil is delivered from the low pressure cylinder 7 through the conduit 34. In the upper part of the valve chamber is a hollow threaded plug 35, the lower part of which is formed into a sleeve 36 in which is slidably mounted the cup member 37. The upper face of plug .35 is provided with an `oil inlet hole 38 closed by the one-way ball valve 39, held closed by the ,spring 40, the lower end of which is seated in' the cup member 37. The spring 40 is provided with bumps or lugs 42 formed on the convolutions of the spring, of such a size that when the spring has been compressed to a certain point these bumps or lugs contact with the adjacent convolutions of the spring and being in solid contact have extremely high further resilient eiect, due to the waves on the adjacent convolutions acting as short elliptical springs; the whole spring acts almost as would a solid rod in holding the ball Valve 39 closed while the low pressure lcylinder is operating. The limited resilient effect is just enough to compensate for wearing down of the staggered depressions on rod 56 or for the tolerance in linear dimensions between valve seat of valve 30 and rod 56.

The plug 35 is provided with a plurality of holes 43 for ready exit of the oil to the valve 115 chamber 32.

In the lower part of the valve chamber y32 is a second hollow threaded plug 44 which tapers into a sleeve 45 in which slides the cup member 46, in which cup member is seated a 120 spring 47 which holds ball 48 against hole 49 in the lower part of the hollow plug, this ball thus forming a one-way valve. The plug 44 is provided with holes 50 for a ready exit of oil into Ithe valve chamber 32.

Leading from the valve chamber 32 is a cylinder 52 in which the piston 53 slides; against the other side of the piston bears the spring 54, the force of which can be adjusted by the threaded plug 55.

The piston 53 is rigidly connected with the rod 56; rod 56 is provided with staggered depressions 57, and 58, so arranged as to co-operate with extensions 59 and 60 on the cup members 37 and 46, so that when one cup member is ex- 135 tended into one of the depressions the other cup member is forced backwardly into its sleeve, as shown in Fig. 4.

Rod 56 terminates in a pin 62 which slides in a guide 63. The movement of the piston 53 to 140 the right is limited by a threaded rod 64, threaded through the plug 55.

When the pressure is lowrthe parts are as in Fig. 4. When the pressure increases beyonda certain predetermined point, piston 53 moves to 145 `the right, allowing cup member 37 to move into 32 into a passage 66 and thence into the power cylinder 67, which is provided with a piston 68 and piston rod 69, on the outer end of which is secured the pusher member 70 provided with an inclined cam face, 72. The pusher member 70 is supported on a plurality of rollers 73 carried by a supporting bed-plate 74.

The rod 69 is formed in its upper edge with ratchet teeth l5 with which the ratchet tooth 76` engages, the tooth being pivoted at 77, so that it falls by gravity into engagement with the ratchet teeth.

A suitable reservoir for the oil is provided, as indicated at 80. This reservoir connects through a pipe 82 with a space 83 at the top of the housing member 30, this space 83 being closed by a cover-plate 84. 1n order that the oil from the reservoir may get into the cylinders 7 and 10 on the suction or recovery strokes, there is provided a threaded plug 85 which is provided with a spring pressed one-way ball valve 86 which admits oil into the small chamber 87 which delivers oil into the passage 88 from which it is sucked through channel 33 into the cylinder 10.

Another threaded plug 90 is provided with a one-way spring pressed ball valve 92 which allows oil to enter into the small chamber 93 from whence it passes through channel 94 into the low pressure cylinder 7.

In order to allow the escape of oil from the power cylinder 67 when it is desired to lower the lifting arm of the jack, there is provided an escape passage 96 which opens into the chamber 97 in the housing member 30. In the upper part of recess 97 is threaded a pipe 98 provided with a bleeder hole 99 controlled by a spring pressed plunger 100. Evidently when this plunger is moved to the left, Fig. 4, oil from the power cylinder will escape through the bleeder passage 99 and flow downwardly through the annular space 102 into the reservoir space 83.

The lifting arm 105 is pivoted on axis 106 to supporting side plates 107 which may be integral with or secured to the side frame members 1 and 2. The lifting arm is of heavy rigid material and is provided with downwardly extending side plates 105 in which is pivoted a roller 108 on an axis 109, in a position to be engaged by the inclined cam face 72 of the pusher member 70, thus forming a lever of the third class. The power arm of this lever is formed by that part of 105 and 105' between the axes 106 and 109. The lifter arm plate 110 is pivoted on the axle 111 on the outer end of the lifter arm and has an extension 112 pivoted to an arm 113 to keep the plate 110 substantially level in its several different positions.

A pair of retracting springs 115 is provided to pull the pusher member 70 back, to effect the lowering of the jack.

An important aspect of the invention is release mechanism which can be operated from a plurality of points, which will now be described.

In order to release the jack, the bleeder valve 100 must be pulled to the left and the ratchet tooth 76 must be raised. To accomplish these movements, there is a control rod 117 rotatably mounted in suitable bearings 118 to extend 1ongitudinally of the jack. This control rod at one end is provided with an extension 119 which is provided with a finger 120 which hooks under the ratchet tooth 76.

At a suitable intermediate point, there is sesured to rod 117 a handle 121 by which it can be readily rotated.

At the handle end of the jack, the rod 117 is provided with an operating member 122 which is sleeved on rod 117, being rotatably held there by a set screw 123 moving in a slot. A spiral spring 124 bears against 122 to tend to move 117 in a counter-clockwise direction, and this spring is strong enough to transmit to rod 117 a turning movement suicient to lift tooth 76 and to open the bleeder valve 100 and is normally not called into use.

The operating handle 13 is provided with a rod 125 operated by the handle 126, 125 being forced upwardly by the spring 127. The lower end of rod 125 is adapted to engage in the tooth segment member 128 which is pivotally mounted on the shaft 15.

The valve 100 is provided with a stirrup extension 130 which is pivoted to a lug 132 slidably fixed to the rod 117. The outer end of the valve 100 passes loosely through a hole 133 in the stirrup 130, and has a cross-pin 134 in its end. This gives a lost-motion connection between the bleeder valve 100 and the rod 117.

The described mechanism operates as follows:-

In releasing the jack, the rst thing the operator does is to pull handle 13 toward him, at the same time lifting on release handle 126. This pumping stroke builds up additional pressure, and so takes the load off the ratchet tooth 76. The pumping stroke is repeated if necessary until suii'icient load is taken off the tooth 76 by the additional pressure to allow rod 117 to lift the tooth. Spring 124 allows as many pumping strokes as may be necessary. After rod 117 has rotated a small amount, and the tooth 76 is released, then the stirrup 13 0 picks up pin 134 and valve 100 and releases the valve. The lost-motion connection between the valve 100 and the stirrup insures the lifting of the ratchet tooth 76 before the bleeder valve 100 is opened. Unless this were so, the ratchet tooth would continue to carry the load.

With bleeder valve 100 open, the springs 115 will retract the pusher member 70, the oil from the power cylinder 67 escaping through bleeder valve 100 back into the reservoir. This counterclockwise rotation of the control rod 117 can be eifected from an intermediate point such as the handle 121 simply by lifting the handle. Or, it can be eiected by the operator lifting handle 126 which pushes rod 125 into engagement with one of the teeth in segment 128, and then pulling the handle 13 towards him. This lifts lug 122 to rotate rod 117.

For an appreciable time after the load has been jacked up,- it is sustained by the liquid pressure and there is very little load on the latch 76. Under these conditions manipulation of the handle 121 will result in release of the latch 76 and opening of the bleeder valve for lowering the load.

Under certain conditions, where the load is unusually heavy, or where there has been slight leakage of liquid, the load may settle back on the latch 76 and it may not be possible to release i the latch by the use of handle 121, although such condition can be remedied to a certain extent by making this handle longer to give additional -lever age. However, in case that leverage is not sufficient, the load would be released by manipulation of the handles 126 and 13 in the usual way.

The non-fouling caster shown in Figs. 8 and 9 comprises the downward extension 135 which has a lateral extending portion 136. The outer face 137 of 136 has a cylindrical curvature, being I bounded however by lines 138 which converge sharply in a downward direction. The lateral faces of the central portion 136 indicated at 139, are substantially in a shape of the frustum of a very flat cone, the base of the cone being defined by one of the circular lines 138. Projecting downwardly and outwardly at an angle to the horizontal from the frusto-conical surfaces 139 are axles 140 on which are mounted caster wheels 141 which are beveled as at 142 to rest at on the floor. lThe wheels 142 are held on the axles 140 by washers and cotter pins 143. The upper part of 135 is mounted in a suitable swivel mounting 144, as is well understood in the caster art. The swivel bearing which carries the caster 1s carried in a double annular row of ball bearings 145 and 146 which take all radial and thrust loads through anti-friction contacts.

While I have illustrated my invention in some detail it should be understood that the invention is not to be limited to the precise mechanisms disclosed, but may be carried out in other ways, as falling within the scope of the claims.

I claim as my invention:

1. A hydraulic jack, comprising in combination a high pressure cylinder, a low pressure cylinder, a power cylinder, and a piston and piston rod for each cylinder, a lazy tongs mechanism connected to the piston rods for the high and low pressure cylinders, and means for applying power to the lazy tongs at a point between the two last named rods.

2. A hydraulic jack, comprising in combination a high pressure cylinder, a low pressure cylinder, a power cylinder, a piston and piston rod for each cylinder, all of the piston rods moving in substantially parallel paths, a lazy tongs mechanism connected to the piston rods for the high and low pressure cylinders, and means for applying power to the lazy tongs at a point between the two last named rods.

3. A hydraulic jack, comprising in combination a long, .low-frame having substantially parallel side members, a power cylinder, and high and low pressure pump cylinders carried by and between the side frame, the high and low pressure cylinders being placed side by side and the piston rods of all the cylinders moving in rectilinear, parallel paths, an operating handle, and lazy tongs equalizing mechanism for distributing the power from the operating handle to the two pump cylinders.

4. A hydraulic jack, comprising in combination a long, low frame having substantially parallel side members, a power cylinder, and high and low pressure pump cylinders carried by and between the side frame, the high and low pressure cylinders being placed side by side and the plston rods of all the cylinders moving in rectilinear, parallel paths, an operating handle, lazy tongs equalizing mechanism for distributing the power from the operating handle to the two pump cylinders, a pusher member, having an inclined cam face, operated from the power cylinder, and a lifter arm in operative engagement with the cam face of the pusher member.

5. In a hydraulic jack, a pumping handle, ratchet mechanism for holding the lifting arm of the jack against retrograde movement, and means associated with the pumping handle and resiliently connected to the ratchet, and actuated by a pumping movement of the handle, for releasing the ratchet, the resilient connection permitting one or more' pumping strokes of the handle, whereby to build up a pressure to take the load oil' the ratchet and permit its release.

6. In a hydraulic jack, a pumping handle, ratchet mechanism for holding the lifting arm of the jack against retrograde movement, means associated with the pumping handle and resiliently connected to the ratchet, and actuated by a pumping movement of the handle, for releasing the ratchet, the resilient connection permitting one or more pumping strokes of the handle, whereby to build up a pressure to take the load oil the ratchet and permit its release, and bleeder valve mechanism connected with and operated by said ratchet release means.

7. In a hydraulic jack, a pumping handle, a

v ratchet for holding the lifting arm of the jack,

a rod for operating the ratchet for releasing it, and a resilient operating connection between the pumping handle and said rod.

8. In a hydraulic jack, a pumping handle, a ratchet for holding the lifting arm of the jack, a bleeder valve, a rod for operating the ratchet and the bleeder valve, and a resilient operating connection between the pumping handle and the rod.

9. A hydraulic jack particularly adapted for lifting heavy objects such as automobiles which comprises a frame, a lever mounted on the frame adapted to carry said objects, power transmitting means adapted to engage the power arm of said lever to lift the weight arm'thereof, fluid pressure operatedv means comprising two units, one of which has a low mechanical advantage and the other a high mechanical advantage, means to operatively connect the said units by means of a toggle joint, means to operate the said units through said toggle joint, and means to automatically shift from the unit having low mechanical advantage to that having high mechanical advantage when the load to be lifted is applied to said weight arm.

BYRON H. SHINN.

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