US1485138A - Lifting jack - Google Patents

Description

Feb. 26 1924.

L. T. JOHNSON LIFTING JACK Filed April '7, 1923 2 Sheets-Sheet 1 HIS ATTORYS INVENTOR Feb. 26, 1924.

L. 'r. JOHNSON LIFTING JACK 2 Sheets-Sheet 2 7 Filed April 7, 1923 H IS ATTOR EYS Patented Feb. 26, 1924.

,485,138 all" FFlc LAWRENCE '1. JOHNSON, 0F BUFFALO, NEW YORK.

LIF'IING AC'K.

App1ieation filed April 7, 1923. Serial No. 630,443.

To all whom it may concern.-

Be it known that I, LAWRENCE T. JOHN- SON, a citizen of the United States, residing in Buffalo, in the county of Erie and State of New York, have invented an Improve-- ment in Lifting Jacks, of which the following is a specification.

My present invention relates to an 1m provement in lifting jacks and more para pump actuated by the motor for forcing the liquid to the lifting piston to operate the same. The motor in this structure while designed to operate automatically will obvious'ly require attention to turn on and shut off the power when the lifting operation is started and when the object to be lifted has been raised to the desired height, as otherwise the motor will continue to operate and to so increase the pressure after the lifting piston has been raised to its maximum extent as to endanger the use of the apparatus by breaking or cracking the lifting piston cylinder or other part or parts of the jack. The principal object of my present invention is to overcome this difficulty and to provide the type of jack shown in the Letters Patent aforesaid with an attachment by which, after the lifting piston and the object to be raised has been lifted a predetermined distance, the motor may continue its operations in driving the pump without in any manner affecting the pressure in the lifting cylinder by which, after the load has been raised a predetermined required distance, the pressure remains constant and the load at the desired level. This is preferably accomplished by providing a device for causing the discharge from the pump to by-pass the channel leading from the pump to the lifting piston. The attachment furthermore is so made as to be adjustable, as hereinbefore intimated, to enable the operator in the use of the jack to raise a load to any predetermined distance within the lifting limits of the jack and to maintain the load in this position without stopping the operation of the motor and pump, This attachment, therefore, operates not only as a means for determining the distance to which the load may be raised, but also as a safety device for the protection of the jack, as will be hereinafter more particularly described.

In the drawing: Fig. 1 is a side elevation of a lifting jack made in accordance with my invention.

Fig. 2 is a central longitudinal section. Fig. '3' is a plan. Fig. 4 is an enlarged transverse section through the valve chest of the motor, and Fig. 5 is a perspective section illustrating the valves and ports of'the motor.

In the lifting jack made in accordance with this invention there is a base 10 in one portionof which there is a socket 11 adapted to receive a cylinder 12 fitted with a plunger 13. At its opposite endsthe plunger.

13 is provided with istons 14 and 15 adapted to be operate hydraulically, as hereinafter described, to raise the head 16 which is suitably connected to the upper or outer end of the piston 14 and to be placed under an object to be lifted in order to raise the same.

Suitably connected to ormade integral with the base of the jack there is a pump cylinder 17. At the lower end of this pump cylinder there is a port 18 fitted with a check valve 19 adapted to bear against a suitable seat and to be normally maintained against the seat by the action of a spring 20 extending between the valve and a plug 21 suitably fixed in the base 10. The port 18 communicates with the passage 22 leading through the base to the lower end of the cylinder '12. In the base 10 and also forming apart of the pump there is a wall through which there is a port 23 fitted with a check valve 24 adapted to bear against a valve seat and to be maintained normally in position against the same by a spring 25 extending between the valve and a plug 26 suitably fixed in the under side of the base 10. The port 23 communicates with a chamber 27 lying beneath the check valve 24 and there is a port 28 connecting the cham-' ber 27 with the interior of the inder. v

The base 10 supports a lower or inner cylindrical member 29 which, at one end, is suitably fitted to the base and at its outer or upper end is provided with apartition wall 30. Above the cylinder 29 is an upper or outer cylinder 31. At one end this is suitably connected to "the partition wall '30 pump cyland at its'opposite end is provided with a. cylinder head 32. These parts of the apparatus may be connected to one another and secured in their operative relationship by means of bolts 33 each suitably connected at one end in the base and passing through and connected to the cylinder head 32. The pump also includes a piston rod 34, at the lower or inner end of which there is secured a piston 35 operating in the pump cylinder.

This piston rod 34 passes through the partition wall 30 and also through a suitable stufling box 36 associated with the partition wall and terminates in the chamber between the partition wall 30 and the cylinder head 32 in the cylinder 31 which, as hereinafter described, is one of the cylinders of the motor. The chamber belhw the partition wall 30, including the space surrounded by the cylinder 29, forms another cylinder for the motor and also provides a reservoir for the suction for the pump. The outer end of the piston rod 34 has connected thereto a piston 37 operating in the cylinder 31 and forming the mainv piston of the motor, while the piston rod 34 is also connected to an auxiliary piston 38 operating in the cylinder 29 and forming the auxiliary pistonof the motor.

Suitably connected to the cylinder head- 32 there is a valve chest 39. Within this valve chest 39 there is a cylinder 40 and the opposite ends of the valve chest are provided with suitable heads or covers 41 and 42. The chest head 41 is interiorly adapted to receive a valve piston 43 which operates therein, and the end of the cylinder 40 adjacent the valve chest head 42 is fitted with a valve piston 44 which, with the valve piston 43, operate the valve 45 which is connected between the valve pistons by a suitable valve rod 46. The chamber in the valve chest head 41, in which the valve piston 43 operates, is indicated at 47, and interiorly the cylinder 40 is provided with a shoulder 48 which limits the movement of the valve piston 44 in one direction and thus in this direction determines the'extent of the movement of the valve 45. The cylinder 40 is provided with an inlet port 49, as shown in Fig. 4, and the valve chest is fitted with a boss to provide for an inlet chamber 50 connecting with which there is a pipe 51 leading from any suitablesource of compressed air or other fluid which is thus supplied to the inletchamber 50 and through the port 49 to the interior of the valve chest. Suitably placed in the cylinder head 32 there is an inlet and exhaust passage 52 which, by means of a pipe 53 and a ort 54, makes communication between the interior of the valve chest and the lower end of thechambar in which the piston 37 operates, In the cylinder head 32 there is also an inlet and exhaust passage 55 making communication between the interior of the valve chest and the chamber in which the piston 37 operates, the passage 55 leading to one side of the piston and the passage 52 to the opposite side of this piston. Also in the cylinder head there is a suitable exhaust passage 56 making communication between the interior of the valve 45 and the atmosphere or other place to which the spent fluid is exhausted. The passage 55 is suitably connected by means of a pipe 57 to a port 58 making communication with the chamber in which the piston 38 operates, the port 58 being preferabl placed immediately below the partition wa l 30.

Suitably associated with the valve chest 39 is an auxiliary valve chest 59. A cylinder 60 is fitted in the auxiliary valve chest providing a chamber 61 for an auxiliary valve 62. The cylinder 60 is maintained in position and the auxiliary valve chest suitably closed by a plug 63 or otherwise.

tending through the wall of the cylinder 40 y and through the wall of the cylinder 60- there is a port 64 making permanent communication between the chambers within the valve chests. There is also a port 65 malting communication between the chamber 61 in the auxiliary valve chest and the space between the valve piston 44 and the valve chest 42 in order that when the port 65 is closed by the auxiliary valve 62 the fluid pressure is shut off from the right hand side of the valve piston 44. as shown in Fi 2,

thereby causing the valve to be moved rom left to right, as viewed in this figure, due

to the difference in the diameters of the" valve pistons. a passage 67 making provision for connecting the exhaust with the space between the valve piston 44 and the valve chest head 42 when the port 65 is closed, as shown in Fig. 5, so as to provide for the exhaust of the fluid between the valve piston 44 and the valve chest head 42. When the auxiliary valve is raised to the position shown in Fig. 4. the pressure on both sides of the valve piston 44 is equalized and consequently the pressure exerted against the valve piston 43 shifts the valve in the opposite direction, namely from right to left, as shown in Fig. 2. The auxiliary valve 62 is operated by an auxiliary valve rod 68 extending through and journaled in a portion of the cylinder 60 and also, if desired, in the plug 63. This auxiliary valve rod extends into the cylinder in which the piston 37 operates and is provided with a shoulder 69 and a head 70. The lower portion of the auxiliary valve rod extends into a bore 71 provided therefor in the upper or outer end of the piston rod 34 and in sodoi-ng passes-through a cap 72 adapted to contact" with the shoulder 69 so that when the piston rod 34 and the pistons associated therewith are moved upwardly the auxiliary valve is raised and There is also a port 66 and when the piston rod 34 and the pistons 37 and 38 reach the end of their stroke in the opposite direction the head 70 contacts with the cap 72 to move the auxiliary valve rod in the opposite direction and to correspondingly shift the position of the auxiliary valve. I

The construction and operation of the parts of the jack as hereinbefore described are similar to those of the-jack made in accordance with the patent to which I have hereinbefore referred, the pistons 37 and 38 being moved inwardly or downwardly to force the liquid from the pump 0 linder through the check valve 19 through t e passage 22 into the cylinder 12 to produce a pressure against the lifting plunger to raise the same, the motor valve mechanism being arranged, as hereinbefore described, to admit the fluid pressure to the corresponding sides of the pistons 37 and 38 simultaneously to effect this movement of the pistons and the pump plunger. The pump plunger and the piston operating the same are moved in the opposite direction by admitting the fluid pressure only between the partition wall and the adjacent side of the partition wall so that the piston 38 is inoperative dur- .ing this return movement of the parts of the pump and the motor actuating the same,

during which return movement, however,

the suction created by the return of the pump piston creates a partial vacuum whereby the check valve 24 is opened to permit the liquid contained in the lower portion of the apparatus to flow to the chamber 27 and the passage 28 to the interior of the pump cylinder. Also as illustrated the jack may be provided In a suitable position with a bracket 73' in which there is mounted a shaft 74 carrying rollers or Wheels 75 upon which, when tilted, the jack may be moved from place to place, and in order to suitably tilt the ack and to move it when and where desired I may also provide a bracket 76 having a rod 77 mounted therein with handles 78 and 79 connected to the rod 77 preferably exteriorly of the arms of the bracket. These features, however, form no art of my premnt lnventlon.

It will be 0 vious that in the operation ofthe apparatus, as hereinbefore described, the pump is set in operation by admitting the fluid under pressure to the motor mechanism driving the same and that after sufficient pressure has been developed to ra se the plunger piston a predetermined distance the power must be shut off as otherwise the motor will continue to operate and may produce a pressure sufficiently great to break the apparatus. In order to prevent this and to control the height to which the lifting piston may be raised I employ a post 80 having a base 81 connected 1n position lever 83 is pivotally coimected as indicated at 84 to the upper end of the post 80. The end 85 of this lever is pivotally connected to a socket 86 surrounding the upper or outer end of the spindle of the check valve 24 as is indicated at 87. The opposite end of this lever 83 is preferably of angular formation as shown at 88 and passes through an opening 89 provided therefor in a wall of the cylinder 29. This opening also provides a means for maintaining an atmospheric pressure below the piston 38 in the cylinder 29. Exteriorly of the cylinder 29, the end 88 of the lever 83 terminates in a head 90. The head 90 preferably' lies on the exterior of the cylinder" 29 and is provided with an opening through which freely passes a sleeve 91. The sleeve 91 at its upper or outer end is suitably connected in a bracket 92 carried by the head of the plunger 13. Within the sleeve 91 I employ a rod 93. At its upper end this rod 93 terminates in-a head 94 and at its inner or lower portion the rod 93 passes through an opening provided therefor in the inner end of the sleeve 91 and adjacent its lower extremity is fitted with a flange 95. Above -the flange 95- the rod 93 carries a washer 96 and the same is yieldingly supported by means of a spring 97 surrounding the lower end of the rod and extending between the flange 95 and the washer 96. In order to maintain the lever 83 and the parts associated therewith in a normal position I may employ a spring 98 suitably connected to the upright 80 and also to the angular arm 88 of the lever.

From the foregoing description it will be understood that the rod 93 is adjustable for obtaining various heights of lifting the jack-head inasmuch as the lower end of the rod is screw threaded and adapted to receive the nut or flange 95 thereon which is adjustable to position for determining the extent of the movement of the rod 93 and consequently the height to which the jack head is lifted.

to overcome the action'of the spring 98 the lever 83 will be swung in a clockwise direction causing the socket 86 to engage the spindle of the check valve 24 moving the check valve from its seat and holding it open in order to permit the liquid to bypass through the valve or inlet passage 23 firstin one direction and then in the other depending upon the direction in which the pump piston operates so that the operation of the pump and motor will not then affect the lifting plunger in any manner whatsoever. The pressure in theplunger cylinder may be released and the liquid which is returned to the suction chamber of the pump by means of a pipe 99 in which a suitable valve 100 for this purpose is placed, or otherwise. Alsoas indicated in the draw ing the head 90 may be provided with a hopper or funnel-shaped member 101 to guide the sleeve '91 intothe position in which it will pass through the opening provided therefor in the said head.

From the foregoing description it will now be understood that with the attachment hereinbefore described the lifting plunger may be raised a predetermined distance and maintained in this position supporting a load without shutting off the power and stopping the motor and without creating any undue pressure and consequent disastrous effects in the lifting jack apparatus.

I claim as my invention 1. In a lifting jack, a cylinder, a lifting piston in the cylinder, a pump cylinder, a pump piston in the same, means for operating the pump piston, there being a passage from the pump cylinder to the lifting piston cylinder and a suction passage to the pump cylinder from a source of supply, a check valve in the passage from the pump cylinder to the lifting piston cylinder, a check valve in the passage from the pump cylinder to the source of supply, and means actuated by the lifting piston for opening and holding open the check valve in the passage from the pump cylinder to the source of supply when the lifting cylinder has been moved a predetermined distance. I o

2. In a liftin lack, a cylinder, a lifting piston in the cylinder, a pump cylinder. a pump piston in the same, means for operating the pump piston, there being a passage from the pump cylinder to the lifting piston cylinder and a suction passage to the pump cylinder from a source of supply, a check valve in the passage from the pump cylinder to the lifting piston cylinder, a check valve in the passage from the pump cylinder to the source of supply, a lever connected at one end to the check valve in the passage from the pump cylinder to the source of supply, means for pivotally supporting the said lever, and means actuating the said lever when the lifting piston has been moved a predetermined distance to then automat ically open the said check valve and hold the same open causing the pump to be inoperative and preventing a further movement of the lifting piston during the contin'ued operation of the pump.

3. In a lifting jack, :1. cylinder, a lifting piston in the cylinder, a pump cylinder, a pump piston in the same, means for operating the pump piston, there being a passage from the pump cylinder to the lifting piston cylinder and a suction passage to the pump cylinder from a source of supply, a check valve in the passage from" the pump cylinder to the lifting piston cylinder, a check valve in the passage from the pump cylinder to the source of supply, a lever, a socket connected at one end of said lever to hold the check valve open in the passage from the pump cylinder to the source of sup,- ply, means for pivotally supporting the sai lever, a sleeve passing through the opposite end of the said lever and connected to the said lifting piston, and means associated with the sleeve and actuated by the same after it has moveda predetermined distance for swinging the said lever and causing the socket to engage with the spindle of the check valve to maintain. the passage open frbm the pump cylinder to the source of supply.

4. In a lifting jack, a cylinder, a lifting piston in the cylinder, a pump cylinder, a pump piston in'the same, means for operating the pump piston, there being a passage from the pump cylinder to the lifting piston cylinder and a suction passage to the pump cylinder from a source of supply, a check valve in the passage from the pump cylinder to the lifting piston cylinder, a check valve in the passage from the pump cylinder to the source, of supply, a lever, a socket connected at one end of said lever to hold the check valve open in the passage from the pump cylinder to the source of supply. means for pivotally supporting the said lever, a sleeve passing through the opposite end of the said lever and connected to the said lifting piston, a rod associated with the sleeve and adapted to be raised with and by the sleeve after the sleeve has been lifted a predetermined distance, and a washer yieldingly mounted on the said rod and adapted to contact,.with the end of the said lever to swing the same to cause the said socket to engage the spindle of the check valve and open the passage from the pump cylinder to the source of supply. 19Signed by me this 10th day of March,

LAWRENCE T. JOHNSON.

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