US2702024A

US2702024A - Automatic mechanical locking device for telescopic jacks

Info

Publication number: US2702024A
Application number: US212327A
Authority: US
Inventors: Harold Robert Edwin
Original assignee: Electro Hydraulics Ltd
Current assignee: Electro Hydraulics Ltd
Priority date: 1950-07-24
Filing date: 1951-02-23
Publication date: 1955-02-15
Anticipated expiration: 1972-02-15

Description

R. E. HAROLD Feb. 15, 1955 AUTOMTIC ,MECHANICAL LOCKING DEVICE FOR TELESCOPIC JACKS Filed Feb. 25,. 1951 3 Sheets-Sheet l AUTOMATIC MECHANICAL LOCKING DEVICE FOR TELESCCPIC JACKs Filed Feb. 23; 1951 Feb. I5, 195252 R..E. HAROLD 3 Sheets-Sheet 2 Wm NM Nv mm LE Y Feb. 15, 1955 R. E. HAROLD K 2,702,024

AUTOMATIC MECHANICAL LOCKING DEVICE FOR TELESCOPIC JACKS Filed Feb. 23, 1951 3 Sheets-Sheet 5 lOl Maw/#MM incorporate a lock.

type a locking spring tongue is mounted either on the` United States Patent Oy AUTOMATIC MECHANICAL LOCKING DEVICE FOR TELESCOPIC JACKS Robert Edwin Hai-oid, Penkeih, Warrington, England, an

signor to Electro-Hydraulics Limited, Warrington, England, a British company This invention relates to automatic mechanical locking devices for telescopic jacks and is concerned with that type of locking device which comprises a locking means, for example spring claws, a lock sleeve through or over which the locking means can slide and a spring biased lock bolt adapted to hold the locking means inl their locking position to prevent their collapsingor extending as the case may be and sliding back through or over the lock sleeve. Locks of this typev are particularly useful for uid pressure operated jacks. y

Some of the known locking devices of this type suier from the disadvantage of having considerable length and when it is desired to incorporate a locking device in a telescopic jack due to the circumstances governed by the use of the jack its length cannot be increased to In one known arrangement of this sliding piston assembly or on the cylinder of the jack, and surrounding the piston, or a lock sleeve carried by the piston, but here again it will be appreciated that the length of the jack has to be increased considerably to include such a locking arrangement.

It is the object of this invention to provide allocking device of the type described in a telescopic jack without appreciable increase in length, thereby overcoming the disadvantages referred to above.

According to the present invention an automatic mechanical locking device of the type described, for use in connection with telescopic jacks, comprises locking means carried by a jack cylinder, co-operating means such as a lock sleeve through which the locking means can slide to effect engagement with the co-operating means, and a movable lock bolt which normally lies in the path of the locking means so that when the locking means approaches the co-operating means, the lock bolt is pushed away by the locking means, but is capable of returning behind the locking means when it is moved into the locking position, and then to hold it firmly in engagement with the co-operating means, the said cooperating means and lock bolt being carried substantially within the jack pistonrod. f

The locking device may include indication means to signify that the locking device is in the locked or unlocked position.

According to this invention also the locking means and co-operating member are duplicated so that the jack can be locked in both the extended or closed position.

Three forms of construction according to this invention are diagrammatically illustrated in the accompanying drawings in which Figures l and 2 show locking means for the closed (Figure 1) and extended (Figure 2) positions in longitudinal section of one form, whilst Figures 3 and 4 are similar views of an arrangement without lock indication means. Figures 5 and 6 show in fragmentary section two further modified forms.

Referring to Figures 1 and 2, the telescopic jack comprises a cylinder 1 having

fluid connections

2 and 33, an end wall 4 formed with anattacliment lug 3, and a screwed in end nut 34, provided with a bore -through which a hollow piston rod 19 can slide. Fixed to the piston rod 19 by a lock sleeve 9 is a piston 21 sliding in the bore of the cylinder. The locking means, in the Vform of a spring tongue or claws 6, is held in the end wall 4 by a shoulder 66 of a spindle 86, which in turn is secured by means of a' nut 5, the part 6 serving for the locking in the closed position, while similar locking 2,702,024 Patented Feb. 15, 1955 rice means 32 serves for the extended position and has a hollow base 31 provided with external threads for securing onto a shoulder 30 in the bore of the piston rod 19. Sliding in the bore of the pitten rod 19 are hollow lock 5, bolts 11 and 36 biased into the locking position by

springs

12 and 37 respectively, an aperture 52 being provided in the piston rod 19 to admit tluid pressure into its bore, l

whilst an eye bolt 68 screwed in the outer end of the piston rod 19 is provided with a breeze hole 67.

The hollow spindle 86 is provided with slots 46 and 41 and carries, or is made integral with, a lock sleeve 35, and carries on its outer end a screwed on nut 38 which serves as a rest for the spring 37. In the bore of the hollow spindle 86 slides a solid spindle 40 provided with l5 slot 69. Slots 50 and 41, also slots 46 and 69, are capable of registering together. The spindle,40 is secured to the lock bolt 36 by a pinV 42, so that lthe spindle 40 is restrained to move together with the lock bolt 36, but both parts are free to move in relation to the piston rod 20 19 and the hollow .spindle 86, as the pin 42 is free to move in the respective slots 41 and 50. interposed between'the hollow spindle 86 and the solid spindle 40 at their inner ends i s a sleeve 70 free to slide between both spindles. A pin 47 is driven into the sleeve 70, while the spring 23 and a washer 48 onto which the spring presses bias the pin into the cylinder. The slots 46 and 69 allow the pin to move in relation to the hollow spindle 86 and solid spindle 40. Onto the cylinder are fixed

pins

25 and 44 round which rocker arms 26 and 43 can pivot. The arm 26 serves as a lock indicator for the'closed position of the jack and the arm 43 as a-flock indicator for the extended position. Glands 15, 16, 17, 18, 28, 53, 54, 55, 56, 57, 58, 59, 60, 78, 79 and 80 provide seals.

The de vice functions in the following manner: Assuming the Jack to be in the extended position (Figure 2) .and it is desired to retract or close the jack to the position shown in Figure 1, liuid pressure is admitted into the Jack cylinder through connection 33 to move-the )ack piston 21to the left, whereupon uid pressure from the left hand side of the piston 2l will be expelled through connection 2. Towards the end of such movement, the spring tongues 6, which are stationary, enter the lock sleeve 9 and are depressed inwardly or collapsed by the sleeve, so as to pass through the sleeve; thereafter the tongues expand, due to their inherent resiliency. During their last part of the travelthrough the sleeve 9, the loclt tongues 6 abut the lock bolt 11 and force it away against the action of its spring 12. Movement of the lock bolt 11 against the spring may be assisted by the tiuid back pressure, the other side of the lock bolt 11 being under in put pressure, due to the iiuid entering the boie of the piston rod 19 by aperture 52. When the spring tongues 6 have passed through the lock sleeve 9 and expanded again, the lock bolt 11, due to the action of the spring and possibly assisted by the uid pressure, forces its way into the spring tongues 6, thereby preventing them from collapsing and sliding back through the lock sleeve 9,` so that the locking device is locked to prevent extension of the jack and this lock will hold the ack in the locked closed position until uid pressure is admitted mtothe cylinder through connection 2 and allowed to be expelled through connection 33. When the lock bolt 11 is forcing its way into the lock tongues 6,

05 in order to lock the jack in its closed position, the lock bolt- 11 contacts the pin 47 to move it against the action of its spring 23, thereby in turn` moving the sleeve and the rocker arm 26 about its pivot 25, thereby providing an indication for the locking position. When the 70 lock is broken, the lock bolt 11 will be carried away by the piston rod 19 so that the rocker arm 26 can return to its original position, thus indicating that the lock is broken.

Assuming the jack to be in the closed position (Figure l) and it is desired to extend the jack tothe posi-v tion shown in Figure 2, tluid pressure is admitted into the jack cylinder through connection 2 acting on the left hand side of the piston 21 moving it to the right,

while the uid from the right handk side of the piston 2l is expelled through connection 33.

. This duid pressure, entering through connection 2,

. passes through the gaps between the lock tongues 6 and acts on the lock bolt 11 to move it against its spring, so that the spring tongues 6 can collapse and the liuid pressure can move the piston 21 to the right, thus extending the jack. As the piston 21 moves to the right, it carries the lock sleeve 9 well over the collapsed lock tongues 6 until they can expand again outside the lock sleeve.

Towards the end of the movement, the spring tongues 32which are carried by the piston rod 19, pass onto the lock sleeve 35 and are forced outwardly or expanded, so as to pass over the sleeve 35. During the last part-of their travel over the sleeve 35, the lock tongues 32 abut the lock bolt 36 and force it to the right against the force of its spring, which movement may be assisted by the uid back pressure. When the spring tongues 32 have passed over the lock sleeve 35 and return to their former position, the lock bolt 36, due to the action of its spring 37, forces its way over the spring tongues 32 thereby preventing them from expanding and sliding back over the lock sleeve 35, so that the locking device is locked to prevent closure of the jack and this lock will hold the jack in the locked extended position until iluid pressure is admitted into the cylinder through connection 33, passes tthrough aperture 52 into the bore of the piston rod 19, through the slots of the lock tongue 32 and acts on the lock bolt 36 to move it against its spring 37, so that the spring tongues 32 can expand and the fluid pressure acting on the piston 21l can move it to the left, carrying the lock tongues 32 over the lock sleeve 35 until they can return to their former shape after passing over the lock sleeve 35.

When the lock bolt 36 is pushed into the locked position by the lock tongues 32, it will carry pin 42 and thus spindle 40 with it, thus rocking the rocker arm 43 about its pivot 44, in order to provide an indication for the locked position on extension. It will be noted that the lock bolt 36 is biassed into a different position whether in or out of lock and this different position of the lock bolt 36, and therefore the associated parts, namely pin 42, spindle v40 and rocker arm 43, will allow remote indication. It will also be noted that spindle 42 and spindle 47 on the other end move in slots so that they do not carry other parts with them.

If no lock indication is desired, the locks may be conveniently in the form as indicated in Figures 3 and 4, in which the same reference numerals used in Figures l and 2 are used again for similar parts, and as the only essential difference between the two constructions is the omission of the lock indicator means consisting of the rocker arms and their associated parts, no detail description is felt to be necessary.

Referring now to Figure of the accompanying drawing, there is provided in the bore of a jack cylinder 100, a slidable piston assembly which comprises a hollow piston rod 101 which is internally threaded at its end for engagement with a lock sleeve 102 which holds in position on the piston rod a piston 103, the lock sleeve abutting against a washer 104 defining one end of the travel of a lock bolt 105 slidably mounted in the bore of the piston rod 101. The said lock bolt 105 is biassed outwardly by one end of a spring 106, the other end of which abuts on a Washer 107 which in turn is held thereby on an internal shoulder 108 in the piston rod. The locking means is in the form of spring tongues'or claws 109 held in one end wall 110 of the jack cylinder, the tongues being formed on one end of an elongated member 111 which is screwed into the end wall and retained by a nut 112 andwasher 113. Suitable fluid-tight seals are provided within the jack. The cylinder is provided with a tluid connection 114 and usual attachment lug The device functions in the following manner: Assuming the iack to be in the extended position and it is desired to retract or close the jack to the position shown in Figure 5, liuid pressure is admitted to the jack cylinder through a port in the right hand end of the cylinder (not shown), to move the sliding piston assembly into the cylinder and towards the end of such movement the spring tongues 109 which are stationary, enter the lock sleeve 102 and are depressed inwardly or collapsed by the sleeve so as to pass through the sleeve; thereafter the tongues expand, due to their inherent resiliency. During the last part of the travel through the sleeve, the lock tongues 109 abut the lock bolt 105 and force this rearwardly against the action of its spring 106. Movement of the lock bolt against this spring may be assisted by the pressure of fluid compressed by the piston 103, and for this purpose the spring tongues adjacent the cylinder end wall are orilced as shown at 116. The washer 107 abutting the internal shoulder 108 in the piston rod is preferably apertured as at 117 to allow venting of pressure on movement of the lock bolt. When the spring tongues 109 have passed through the lock sleeve and expand again, the lock bolt 105, due to the action of its spring, forces its way into the spring tongues, thereby preventing them collapsing and sliding back through the lock sleeve, so that the locking device is locked to prevent extension of the jack, and this lock will hold the jack in the locked closed position until uid -pressure is admitted, to the other end of the cylinder through connection 114. This uid pressure passes through the orifices 116 in the spring tongues 109 and acts on the lock bolt 105 to move it against its spring, so that the spring tongues can collapse and allow liuid pressure to act on the sliding piston assembly to extend the jack. As the jack extends the lock sleeve 102 passes over the collapsed lock tongues 109 until they can again expand outside the lock sleeve.

When it is desired to obtain an indication at a place remote from the jack, that the jack is lockedI or unlocked, the form shown in Figure 6 may be employed. In this figure like reference numerals are used for like parts in Figure 5. In this arrangement there is provided a spindle 118 which passes through the spring tongues 109 and is biassed by a spring 119 into engagement with the lock bolt 105, the other end of the spindle passing out throughI the cylinder end wall 110. The spindle is slidable within the end wall and is adapted to makecontact with one end of a bell crank lever or rocker 120 which is provided on its other end with a screw and nut arrangement 121, which is capable on movement of the rocker of operating a remote indication, for example an electric switch (not shown). In this arrangement when the spring tongues 109 have passed through the lock sleeve 102 and the lock bolt 105 has returned to its normal position, due to the action of its spring, the lock bolt contacts the head of the spindle 118 to move it against the action( of its spring 119, thereby in turn moving the rocker 120 about its pivot 122 sov that the screw and nut device 121 will operate the indication means to show that the locking device is in the locked position. When, however, the locking device is moved to the unlocked position as described with reference to Figure 5, the lock bolt 105 is moved away from the spindle 118 which, due to its spring, tends to follow up movement of the lock bolt, thereby allowing the rocker 120 to move in the reverse direction to indicate that the locking device is in the unlocked position.

Instead of providing lock spring tongues, the locking means may comprise balls or segments of any known type and, for example, may be of the form described in the specification of our co-pending United States application Serial No. 173,608, tiled July 13, 1950, now Patent 2,685,275 issued August 3, 1954.

I claim:

l. A telescopic jack automatic mechanical locking device comprising a jack cylinder, a hollow piston unit including a piston and piston rod slidable in, said cylinder, locking means comprising a plurality of spring claws fast with the cylinder, lock cooperating means and a lock bolt, both carried substantially wholly within said piston unit,

said cooperating means comprising a sleeve carried by and projecting within said piston rod and forming means for securing said piston to said piston rod, said lock bolt being movable vin two directions relative to said piston unit and being arranged in the path of said locking means, and means biasing said lock bolt for movement in one of said directions towards said locking means upon movement of said piston unit in such direction, said locking means being movable through said cooperating means upon movement of said piston unit in said one direction, and said lock bolt being engageable by said locking means during such movement, to be pushed thereby against said biasing means in the other of said directions relative to said cooperating means, said locking means having portions biased into locking engagement with said cooperating means and said lock bolt being movable by said biasing means into contacting relation with said portions of said locking means when said portions of said locking means s engage said cooperating means, to maintain such engag ment.

2. A telescopic jack automatic mechanical locking device comprising a jack cylinder, a hollow piston unit 1ncluding a piston and a piston rod slidable in said cylinder, means for introducing iluid under pressure to said cylinder, locking means comprising a plurality of spring claws fast with the cylinder, lock cooperating means and a lock bolt both carried substantially wholly within said piston unit, said cooperating means comprising a sleeve carried by and projeetingwithin said piston rod and forming means for securing said piston to said piston rod, said lock bolt being movable in two directions relative to said piston unit and being arranged in the path of said locking means, and means biasing said lock bolt for movement in one of said directions toward said locking means upon movement of said piston unit in such direction, said locking means being movable through said cooperating means upon movement of said piston unit in said one direction, and said lock` bolt having an end area subject to pressure in said cylinder to move said lock bolt against said biasing means in the other of said directions relative to said cooperating means, said locking means having portions biased into locking' engagement with said cooperating means and said lock bolt being movable by said biasing means into contacting relation with said portions of said locking means when said portions of said locking means engage said cooperating means, to maintain such engagement.

3. A telescopic jack automatic mechanical locking det vice comprising a jack cylinder, a hollow piston unit including a piston and piston rod slidable in said cylinder, locking means comprising a plurality of spring claws fast with the cylinder, lock cooperating means and a lock bolt, both carried substantially wholly within said piston unit, said cooperating means comprising a sleeve carried by the `piston rod and into which said spring clawsare movable,

said lock bolt being movable in two directions relative to said piston unit and being arranged in the path of said locking means, means biasing said lock bolt for movement in one of said directions towards said locking means upon movementof said piston unit in such direction, said locking means being movable through said cooperating means upon movement of said piston unit in said one direction, and said lock bolt being engageable by said locking means during such movement, to be pushed thereby against said biasing means in the other of said directions relative to said cooperating means, said locking means having portions biased into locking engagement with said cooperating means and said lock bolt being movable by said biasing means into contacting relatlon with said portions of said locking means when said portions of said locking `means engage said cooperating means, to maintain such engagement, a spindle extending through said claws, a spring biasing said spindle into engagement with said lock bolt, said cylinder having an end wall through which said spindle is slidable, and a rocker mechanism externally of said cylinder engageable with said spindle to be actuated thereby to form indication means.

4. A telescopic jack automatic mechanical locking device comprising a jack cylinder, a hollow piston unit including a piston and piston rod slidable in said cylinder, locking means carried by said cylinder, lock cooperating means and a lock bolt, both carried substantially wholly within said piston unit, said lock bolt being movable in two directions relative to said piston unit and being arranged in the path of said locking means, means biasing said lock bolt for movement in one of said directions toward said locking means upon movement of said piston unit in such direction, said locking means being movable through said cooperating means upon movement of said piston unit in said one direction, and said lock bolt being engageable by said locking means during such movement, to be pushed thereby against said biasing means in the other of said directions relative to said cooperating means, said locking means having portions biased into locking engagement with said cooperating means and said lock bolt being movable by said biasing means into contacting relation with said portions of said locking means when said portions of said locking means engage said cooperating means, to maintain such engagement, a second locking means carried by and arranged within said piston rod, a second cooperating means within said piston rod fixed against axial movement, a second lock bolt slidable in said piston rod, and means biasing said second lock bolt in one direction, said second locking means being engageable with said second cooperating means and with said second lock bolt, and said second lock bolt being movable against its biasing means to release said second locking means from said second cooperating means.

5. A telescopic jack automatic mechanical locking device comprising a jack cylinder, a hollow piston unit including a piston and piston rod slidable in said cylinder, means for introducing uid under pressure to said cylinder, locking means carried by said cylinder, lock cooperating means and a lock bolt both carried substantially wholly within said piston unit, said lock bolt being mov* able in two directions relative to said piston unit andbeing arranged in the path of said locking means, means biasing saidlock bolt for movement in one of said directions toward said locking means upon movement of said piston unit in such direction, said locking means being movable through said cooperating means upon movement of said piston unit in said one direction, and said lock bolt having an end area subject to pressure in said cylinder to move said lock bolt against said biasing means in the other of said directions relative to said cooperating means, said locking means having portions biased into locking engagement with said cooperating means and said lock bolt being movable by said biasing means into contacting relation with said portions of said locking means when said portions of said locking means engage said cooperating means, to maintain such engagement, a second locking means carried by and arranged within said piston rod, a second cooperating means within said piston rod xed against axial movement, a second lock bolt slidable in said piston rod, means biasing said second lock bolt in one direction, said second locking means being engageable with said seeond cooperating means and with said second lock bolt, and said second lock bolt being movable against its biasing means to release said second locking means from said second cooperating means, and two rockers having mechanicalA connection with the respective lock bolts, one rocker indicating the closed position of the jack and the other indicating the extended position of the jack.

References Cited in the le of this patent UNITED STATES PATENTS 2,295,961 Meyer Sept. 15, 1942 2,434,828 Ashton Jan. 20, 1948 FOREIGN PATENTS 4362,577 Italy Aug. 30, 1938 493,471 Great Britain Oct. 10, 1938 579,294 Great Britain July 30, 1946 615,401 Great Britain Jan. 5, 1949 715,461 Germany a Dec. 22, 1941