US2018148A - Safety control for mechanical garage jacks - Google Patents

Description

E. M. PFAUSER Oct. 22, 1935.

SAFETY CONTROL FOR MECHANICAL GARAGE JACKS 5 Sheets-Sheet 1 Filed Dec. 15, 1953 frzzfeniofiv Fdwarci Oct. 22, 1935. E. M. PFAUSER 2,018,143

SAFETY CONTROL FOR MECHANICAL GARAGE J'ACKS Filed Dec. 15, 1935 5 Sheets-Sheet 2 A Jflz/mfw? Edward/H 114 Oct. 22, 1935. E. M. PFAUSE R 2,013,148

SAFETY CONTROL FOR MECHANICAL GARAGEJACKS Filed Dec. 15, 1933 5 Sheets-Sheet s Oct. 22, 1935. PFAUSER 2,018,148

SAFETY CONTROL FOR MECHANICAL GARAGE JACKS Filed Dec. 15, 1933 5 Sheets-Sheet 4 4/2 Jig 7 1 n M4! 50 Q F1/06 Oct. 22, 1935. E. M. PFAUSER 2,018,148

SAFETY CONTROL FOR MECHANICAL GARAGE JACKS Filed Dec. 15, 1955 5 Sheets-Sheets {A s 4 Q no Q & y A W g Ilium i g A Q V 5% m Jm/nfoi? 1 iafzz/arziflifl awer Patented Oct. 22, 1935 UNITED STATES PATENT OFFICE SAFETY CONTROL FOR MECHANICAL GARAGE JACKS ration of Wisconsin Application December 15, 1933, Serial No. 702,455

19 Claims.

The present invention relates generally to lifting jacks and similar devices and is particularly concerned with floor supported jacks of the mechanical type used around garages, repair shops and the like for raising one end of an automobile. Generally, such mechanical floor supported jacks are arranged for manual operation by utilizing oscillatable handle means by which the lifting mechanism of the jack may be actuated, both in the raising and in the lowering of the load.

Lifting jacks of the mechanical type, and particularly those employing oscillatable handles for actuating the mechanism, generally include some form of ratchet escapement mechanism whereby, in one position of adjustment, the load can be progressively raised and, in another position of adjustment, the load can be progressively lowered, both positions being under the control of the lifting handle. Where the load is thus raised or lowered in a step by step manner, the operative mechanism of the jack includes means for holding the load in position when the lifting handle is advanced to a new position, and then the load is imposed on the lifting handle so that the operation of the latter may raise or lower the load another step, and then the holding means becomes again operative to hold the load in that position while the lifting handle is again advanced to another position. In this way, the reaction of the load being either raised or lowered is imposed first on one means and then on the other means, and in many jacks the escapement mechanism is such that the load will automatically lower itself, the handle swinging in pendulum like fashion and having imparted thereto sufficient momentum by the reaction of the load thereon.

In this so-called automatic lowering or downward ratcheting of the load, the lifting handle may acquire considerable momentum. Not only is this undesirable from the point of the serious impact stresses imposed on the mechanism of the jack but, in addition, the relatively rapid whipping of the operating handle back and forth is dangerous and may inflict serious injury to persons accidentally struck by the handle, as when attempting to seize the handle to stop the lowering of the load. Another undesirable aspact of this type of jack in which, once started, the load will automatically lower, lies in the possibility that a mechanic may be seriously injured when working under a car supported on such a jack if, for any reason, the handle is set in motion in such a way that the reaction of the weight of the car is sufficient to continue the oscillation of the handle. Under these conditions it is not unlikely that the car would be lowered to such an extent and at such a rate that-a mechanic or other person under the car would be crushed. 5

The principal object of the present invention is to eliminate these undesirable conditions, and to this end the present invention contemplates the provision of means responsive to the velocity of the lifting handle or associated mechanism for 10 automatically preventing the automatic continuation of the lowering of the load. That is to say, whenever the lifting handle acquires a velocity which is dangerous, the present invention provides means responsive to this velocity for 15 restraining further movement of the lifting or operating handle under these conditions. Under many conditions, to provide a jack wherein the load will automatically lower itself, the rapid oscillation of the operating handle may introduce severe racking stresses into the jack, and these stresses may be so objectionable that it becomes desirable to eliminate any possibility that any load supported by the jack will automatically lower itself. Under other conditions, it may be possible to provide for the automatic lowering of relatively light loads wherein the whipping of the handle would not be dangerous, but if heavier loads are allowed to automatically lower themselves, it may be that the whipping of the handle would occur at a dangerous rate. According to the present invention, the provision of means responsive to the velocity of the lifting handle during the automatic lowering operation entirely eliminates the objectionable fea tures in both of these jacks. That is, the means responsive to the velocity or impact of the lifting handle may be so adjusted or arranged as to permit a limited amount of automatic lowering, or such means may be arranged to allow no automatic lowering whatsoever.

Briefly, the present invention resides in the provision of means interposed in the jack mechanism and operative to restrain movement of the lifting handle when there is any tendency for 45 the handle to acquire a rate of movement which would be undesirable for any reason. Generically speaking, therefore, the present invention may take two forms, one in which all automatic lowering above a certain critical velocity is prevented, and another form in which all automatic lowering whatsoever is eliminated.

Another object of the present invention is to provide means which is either mechanical or hydraulic for preventing the continuation of the is undesirable.

To this end, an object of the present invention is the provision of means adapted to be j subjected to the impact of the jack operating handle for automatically throwing the jack mechanism into raising position, whereby during the lowering operation if the jack should get out of control and the oscillations of the handle back and forth acquire dangerous velocities, the automatic lowering of the load under those conditions will be discontinued. In this connection, another object of the present inventionis the provision of means moved into biased position when the jack mechanism is shifted into position to allow'the load to lower, which biased means is controlled by latch means adapted to release the biased means when the whipping I of the handle becomes dangerous or when the velocity of the handle approaches a point which would be sufiicient to cause the load to lower itself, a release of the biased means serving to automatically throw the jack mechanism into load raising position-This will automatically terminate the oscillations of the operating handle.

It-is also an object of the present invention to provide'hydraulic check means for a similar purpose, and to this end the present invention contemplates the provision of a hydraulic cylinder and piston arrangement'associated with the jack mechanism in a novel manner so that, while the normal lifting velocities of the jack'mechanism are accommodated, when the velocity of the operating parts assumes dangerous proportions, either by the tendency of the load to automatically lower itself or otherwise, the check means will come into operation so as to reduce the velocity or momentum of the operating parts to a point, either below any critical or dangerous velocities or where the first movement of the *jack mechanism is entirely prevented. More specifically, the present invention contemplates arranging a hydraulic check device interposed between the oscillating portion of the jack operating mechanism and the jack frame and providing the check mechanism with means arranged to automatically permit practically unrestrained movement of the oscillating parts below a critical velocity but restraining movement thereof when there is any tendency for such parts to assume a velocity greater than is desirable. V

This is an important feature of the present invention from a standpoint wholly aside, from its advantage as a means for preventing undesirable whipping of the handle and as a means for preventing, either partially or wholly, automatic lowering of the jack under load. Reference was made above to the fact that in mechanical shops there are usually provided holding and lifting pawl means which are alternately subjected to the loadon the jack, both during the lifting and the lowering operations. This transfer of the load reaction from one part to another necessarily subjects these parts to certain stresses incident to the imposition and the removal of the weight of the load thereon. Now, according to the principles of the present invention, where hydraulic check means are associated with certain of the oscillating parts of the jack mechanism, and where the hydraulic mechanism is arranged to come into effective operation upon the occurrence of excessive velocities, the sudden application of the stresses incident to the transfer of the load from the lifting to the holding pawl means and vice verse. is to a surprising extent effectively cushioned by the hydraulic check means of the present invention. That is to say, the transfer of the weight of the load from the holding means to the lifting means necessarily produces some jerking and racking stresses which, in the prior art of which I am aware, must necessarily be taken care of by the strength and weight 7 of the jack mechanism itself, but where hydraulic 10 check means is provided, such suddenly applied stresses are to a great extent cushioned and absorbed by the hydraulic check. Not only does this protect the jack mechanism from abnormal stresses but, in addition, these stresses are not imposed on the lifting handle so that the opera- 7 tion of the jack is much smoother and inherently more easily controlled than where the op eratorsarms are subjected to the jerking of the handle when the load is being raised or lowered. 'It is thus an important object of the.

present invention to achieve all of these advanthe lifting arm are at a minimum.

Still further, another object of the present invention is the provision of improved liftingv jack construction wherein the side frames of the jack are secured to the mechanism housing in an improved manner.

These and other objects and advantages of the present invention will be apparent to those skilled in the art after a consideration of the following detailed description of the preferred structure taken in conjunction with the accom- 40 panying drawings.

In the drawings: 7

Figure 1 is a top plan view of a jack embodying the principles of the present invention;

Figure 2 is a longitudinal vertical section of 40 the jack shown in Figure 1 and illustrating the relation of the hydraulic check and the means for limiting the movement of the lifting arm;

Figure 3 is a section taken approximately along K the line 3-3 of Figure l and showing the ratchet mechanism and the reversing device for controlling the operation of the lifting and holding pawls;

Figure 4 is a section similar to Figure 3 and showing the relation of the parts when the jack is arranged for lowering theload;

Figure 5 is a section taken approximately along the line 55 of Figure 2;.

' Figure 6 is an enlarged section similar to Figures 3 and 4 but, in addition, shows the application of the biased slide which is operative to throw the jack into raising position when the lifting Referring now to the drawings, particularly Figure 1, it will be observed that the lifting jack constructed according to the principles of the present invention embodies a jack frame indicated in its entirety by the reference numeral I and includes a jack mechanism housing 2 and side frames 3 and 4. The jack is supported at its front or lifting end on supporting wheels 6 and I journaled on suitable axle means 8, appropriately mounted at the forward ends of the side frames 3 and 4. At the rear or handle end of the frame a pair of caster wheels 9 and I!) are disposed, being carried by lateral extensions I 2 and I3 secured to or forming a part of the housing section 2.

The lifting mechanism proper, that is, the parts of the jack which are adapted to engage and raise the load, consists of a rigid lifting arm l5 pivoted or journaled on a pin l6 suitably anchored to the side frames 3 and 4. At its outer or lifting end a load supporting saddle member I8 is pivotally carried, as at l9, and is connected by means of links 20 with the two side frames 3 and 4. The lower end of each of the links is connected by means of a pivot bolt 2| with the associated side frame member, and the upper ends of the links 29 are connected with the saddle member l8 by means of a pivot pin 22, The principal function of the rigid lifting arm i5 is to raise the load supported on the saddle member l8, and the principal function of the links 20 is to hold the saddle member l8 with its upper portion in substantially horizontal load engaging position. Cooperating lugs 23 are formed on the upper portion of the lifting arm l5 and the lower portion of the saddle member l8, and are adapted, as shown in dotted lines in Figure 2, to prevent raising the lifting arm too far. Lugs 24 are formed on the frame members 3 and 4 in a position to cooperate with the links 20 to limit the downward movement of the lifting mechanism, as also shown in dotted lines in Figure 2.

A thrust bar 25 consisting of two sections 26 and 21 connected together by suitable pins 28 is connected at its forward end with a pivot pin 29 carried by the lifting arm l5, and at the rear end of the thrust bar 25, the bar sections 26 and 2'! are pivotally connected, as by a pivot pin 39, with a rack bar 3| forming a partof suitable operating mechanism disposed within the housing 2 and indicated in its entirety by the reference numeral 35. The two side frames 3 and i are reinforced intermediate their ends by means of a suitable spacing member 45, and the side frames 3 and 4 are fixedly secured to the housing 2 by a plurality of studs or cap screws 4! carried by apertured bosses 42 formed at the rear ends of the side frames 3 and 4 and threaded into suitable openings in the housing 2, as best shown in Figures 2 and 3. In this manner the studs or cap screws act in tension to securely hold the rear ends of the side frames 3 and 4 in abutting relation against the forward end of the main frame housing 2.

The mechanism enclosed within the housing 2 for operating the lifting arm l5 will now be described. Referring more particularly to Figures 1 and 2, it will be observed that the rack bar 3! is slidably mounted on a ledge portion 45 carried by the lower section it of the housing 2. The rack bar 3| is provided with teeth 41 which are engaged by the teeth of a pinion 48 carried by a pinion shaft G9 to which a ratchet wheel 56 is secured in any desired manner. As will be obvious, rotation of the ratchet pinion 48 will shift the rack bar 3! fore and aft in the jack frame I and will thereby shift the thrust bar 25 longitudinally to raise or lower the lifting arm l5 and the load supported thereby. The mechanism for operating the ratchet wheel 5% includes a lifting handle 53 formed of tubular stock secured to a handle yoke 56 having arm portions 55 and 56 '5 An oscillating segment 10 is mounted for swing- 5 ing movement about the of the pinion shaft 49 and, for this purpose, is provided with a pair of arm portions H journaled on a cylindrical extension 12 of the ratchet wheel 50, as best shown in Figure 5, and on a cylindrical bushing 13 dis- 2'0 posed on the shaft 49 on the opposite side of the pinion 43. The central portion of the oscillatory segment is provided with a number of recesses M, any one of which is adapted to be engaged by the handle plunger 62, the particular recess 14 en- 25 gaged serving to determine the operating position of the lifting handle 53. The arm portions ll of the oscillatory segment 10 are disposed within a slot 15 formed in the upper curved portion 16 of the housing 2. 30"

The laterally spaced arm portions H of the oscillatory segment IE! are extended downwardly within the housing 2 and are connected together, as indicated by the reference numeral 80, to receive a pivot pin 8i on one end of which a lifting pawl 82 (Figure 3) is mounted. If desired, of course, the lifting pawl may be rigidly secured to the pin 81. Also, as best shown in Figure 2, certain portions of the hydraulic check mechanism, later to be described in detail, are preferably 40 mounted on the pivot pin 8|. A coil spring 33 (Figure 5) serves to bias the lifting pawl upwardly into engagement with the ratchet wheel 50.

As best shown in Figures 3 and i, a holding pawl 90 is journaled on a fixed shaft 9| mounted 45 in the lower housing section 46 and is provided with suitable spring means or the equivalent for swinging the same upwardly into engagement with the ratchet wheel 56. When the parts are disposed as indicated in Figure 3, oscillation of the 501 handle 53 will shift the lifting pawl 82 back- Wardly and forwardly to advance the ratchet wheel 50, the holding pawl 99 serving to retain the ratchet wheel 50 in its advanced position. In this manner the ratchet pinion 48 will thrust the 55 bar 25 forwardly, to the right as viewed in Figure 2 and to the left as viewed in Figure 3.

The mechanism for permitting the load to lower under the control of the oscillatory lifting handle 53 will now be described. The mechanism 60 employed is similar to that disclosed and claimed in the copending application filed by Sigmund Mandl and myself on April 12, 1933, Serial No. 665,675, now Patent No. 1,983,601, granted Jan. 22, 1935, and I do not intend to claim any of the features claimed in that application.

Referring now to Figures 3 and 4, it will be observed that the lifting pawl 82 is provided with a cylindrical stud or lug I90 and that a similar 70 stud or lug if]! is carried by the holding pawl 90. As indicated in Figure 5, these lugs extend laterally from the outer face of the pawls and in a position to be engaged by a member I62 in the form of a reversing cam having slots I03 and H14 bosses receiving the tension stud M.

by which the member I02 is slidably mounted on a pair of pins I05 and I06 fixed in the housing 2, preferably in the upper section thereof. The reversing cam member I02 is biased for movement toward the forward'end of the jack frame by a tension spring I08, the latter being anchored, as at I09, to an ear formed on one of the threaded As is obvious, the force of the spring tends to hold the cam member I02 in the position shown in Figure 4.

The reversing cam member I02 is provided with two cam portions II 2 and H3, the former being disposed adjacent the holding pawl 90 and the latter being disposed adjacent the lifting pawl 82. The rear cam portion I I3 merges into a rear section I I4 of the cam and is provided with a recess II5 (Figure 4) in which a locking arm H6 carried by a locking shaft II! is adapted to be disposed so as to hold the cam member I02 in the position shown in Figure 3, namely, at the rear of thehousing 2 with the spring I08 in tensioned condition.

With the parts in the position shown in Figure 3, it will be observed that the cam sections H2 and H3 are out of the path of movement of the lugs I and MI and that both the lifting pawl 82 and the holding pawl 90 are in a position to engage the teeth on the'ratchet wheel 50.

When the lifting handle is swung back and forth, the lifting pawl 82 will engage the ratchet wheel and will advance the same, turning the wheel in a clockwise direction as viewed in Figure 3, and the holding pawl 90 serves to retain the ratchet wheel in advanced position. The rotation of the ratchet wheel, as will be understood, advances the rack 3I to the left as viewed in Figure 3 and, acting through the thrust bar 25, will raise the lifting arm I5. 3

Afoot pedal I20 is mounted on the end of the lock shaft II'I' outside the casing, as best shown 7 in'Figure '1 and, by stepping on the pedal I20, the

locking arm II6 may be rotated in a counterclockwise direction, moving the arm out of the recess I I and allowing the spring I08 to move the reversing cam I 02 toward the position shown in Figure 4,

In this position the reversing "cam I02 provides for, the loweringof the load supported on the lifting arm I5 by the oscillation of the lifting handle. Referring now to Figure 4, if the lifting handle 53 be raised, the ratchet wheel 50 will be rotated by the reaction of the load in a counterclockwise direction, and the movement of the lifting handle 53 upwardly will shift the lifting pawl. 82 to the right as viewed in Figure 4, the

' load being supported on the lifting pawl. After teeth on the ratchet wheel with sufiicient force so that the subsequent raising movement of the handle 53 will permitthe lifting pawl 82 to be shifted further to the right, and this movement will carry with it the reversing cam I02 until the 7 front cam section II 2 shifts rearwardly an amount sufficient to permit the holding pawl 90 to'rotate in a clockwise direction, as viewed in Figure 4, to the point where the load of the ratchet wheel is sustainedby the holding pawl 90 and no longer by the lifting pawl 82. As soon as the latter is released of the load reaction, the tension of thespring I08 is sufficient to snap the cam plate I02 forwardly, the high part of the cam II3 then riding over the lug I00 of the lifting pawl until the front'cam section II2 engages withrthe lug IOI. In this position of the parts, the lifting handle 53 may then be lowered, shift- -='5 ing the lifting pawl 82 forwardly over the cam section I I3 for engagement with the ratchet wheel 50 ata new position. The subsequent lowering of the lifting handle 53 will then cause the load on the ratchet wheel to be sustained again by the 10. lifting pawl 82, but as soon as the latter takes the load reaction, the tension of the spring I08, acting through the front cam section I I2 and the lug IOI, will swing the holding pawl 90 out of engagement with the ratchet teeth. on the wheel 50, whereupon the lifting handle 53 may be raised to lower the load until the lug I00 engages the cam section II 3 and again reverses the pawls 82 and 90 so that the latter sustains the load and the lifting pawl may again be advanced to engage through the rack 3I and ratchet wheel 50 to the lifting pawl 82 on the oscillating segment directly to the lifting handle 53. If the handle should at this time be released, the efiect'of theload is to swing the handle 53 upwardly with considerable velocity, depending upon the weight supported on r the lifting arm I5. Under these conditions the handle 53 will reach its upper limit of movement with considerable inertia and, at about the same time, the cam member I02 will reverse the pawls so that the load is momentarily sustained on the 40 holding pawl 90 while the lifting pawl '82 is freed from the ratchet teeth. Due to the aforesaid velocity with which the handle 53 reaches its u per limit of travel, the handle will rebound therefrom with considerable force downwardly toward 45 its lower position shown in Figure 4. If the force of rebound is suiiicient, the inertia of the'handle 53 will be sufiicient to momentarily rotate the ratchet wheel .50 in a clockwise direction, as viewed in Figure 4, and as soon as the ratchet wheel 50 is rotated even a slight amount, the holding pawl 30 will be released so that the spring I08 shifts the cam I02 forwardly to the, position, shown in Figure 4 so as to positively hold the holding pawl 90 out of engagement with the cam. 55 At this moment, then, the reaction of the load is again imposed on the lifting pawl 82 and the handle 53 will once more be swung upwardly with considerableyiolence, and if the velocity of the handle is suflicient, as mentioned above, the handle will rebound therefrom with suilicient force to again sustain the loadmomentarily so as to reverse the pawls. In'this way, then, ratchet escapement mechanism of this type will permit the automatic lowering of the load under its own weight, the lifting handle 53 acting as a pendulum for permitting the ratchet wheel 50 to advance in a counter-clockwise direction as 'viewed in Figure 4.

Automatic lowering of the load may or may not be a desirable characteristic of the jack. The rapid oscillation or whipping of the handle is, in the first place, inherently dangerous to persons nearby, even though the handle flies back and forth with only moderate velocity, for even under these conditions, if a person is struck by the handle a serious injury may result. In the second place, the jack is subjected to considerable racking stresses due to the transfer of the load reaction from the holding pawl to the lifting pawl and vice versa, this transfer of load being made suddenly at about the same time that the handle 53 reaches its lower position in one case, and in the other case a transfer of the load from one pawl system to the other is made at about the same moment that the handle 53 rebounds at its upper limit of travel. Where the load which is being lowered in this manner is quite heavy, the racking stresses set up in the jack may become quite severe, and at times jacks operated in this manner have been known to be subjected to such violent oscillations of the lifting handle that the rear wheels momentarily leave the floor.

In the third place, where the jack employs reversible mechanism, that is, mechanism of the escapement type in which the oscillations of the handle may automatically lower the load, it may come about that the operator in manually lowering the load through the control of the lifting handle, accidentally releases the lifting handle, and if the load supported on the lifting arm I is relatively heavy, the handle may be thrown back and forth with sufiicient velocity that it would be impossible for the operator with any degree of safety to seize the rapidly moving handle. If there should happen to be, at this time, a mechanic under the automobile, he would be in considerable danger of being crushed by the descending load, due to the inability of a person to grasp the handle under these conditions.

In order to eliminate these disadvantages and dangers, the present invention contemplates the provision of means for terminating any whipping or rapid oscillation of the lifting handle under unrestrained lowering conditions where the velocity of the lifting handle would be dangerous. Referring now to Figure 6, the means for preventing the continuation of the automatic lowering, that is, under the momentum and by the pendulum action of the lifting handle 53, comprises a biased member I25 slidably mounted within the casing 2 on the pin I06 which supports the cam member I02. The slidably mounted member I25 includes an abutment projection I26 and an elongated notched portion I2'I adapted to receive a spring I28 disposed between a shoulder I23 formed by the notch I21 and the pin I05 which cooperates with the pin I06 in supporting the reversing cam member I02. The rear end of the slidably mounted member I25 has a slot accommodating the pin I06, and the forward end of the slide I25 is provided with a lug I3I thereon with a shouldered section I32 facing the notch I21 and a biasing spring I28 disposed therein. The projecting lug I26 on the lower edge near the rear end of the slide I25 is adapted to engage the outer end of the cam locking arm H6, and for this purpose the arm I I6 may be rounded, as indicated at I35, and 2. lug I36 is carried bythis end of the arm for engagement with the recess I I5 on the reversing cam member I02 described above.

As mentioned above, when the pedal I20 is depressed the arm H5 is swung in a counterclockwise direction, as viewed in Figure 6, so as to shift the arm out of the position shown in this figure, where the reversing cam member I02 is positively locked in a position to permit the ratchet mechanism to raise the load, and in doing so the rounded end I35 of the arm I I6 contacts with the lug- I26 on the slide I25 and forces it towards the left, as viewed in Figure 6, against the tension of the spring I28. A latch lever I40 is pivotally mounted within the housing 2 on trun- 5 nions MI and I42 journaled in suitable supporting brackets carried by the housing, and this latch lever I40 is provided with an operating arm I43 and a weighted portion I44 having a lug I45 which is adapted to be engaged against the shoulder I32 when the slide I25 has been shifted to the left as viewed in Figure 6: so as to hold the slide in latched or biased position.

The latch lever I43 is so disposed within the casing as to be in the path of movement of a nose or lobe I50 carried on one of the arms 'II of the oscillatory segment I0. A companion lobe or projection I5I is disposed below the outer end of the arm I43, the shouldered projections I50 and I5I being carried by the segment arm II adjacent the ratchet wheel 50.

To limit the oscillatory movement of the segment I0, the rear end of the casing 2 adjacent the rounded portion 16 is formed with a flat boss or ledge I55 with which one end of the segment 25.

I0 is adapted to engage in the lower position of the lifting handle 53, as shown in Figures 2 and 11, and the oscillatory movement of the segment 10 in the other direction is limited by the engagement of the arms II with one end I56 of the slot 15 through which the segment arms II extend, this position of the parts being indicated in Figure 9. Obviously, of course, the lower edge of the slot 15 may be relied upon to serve as a stop for the segment I0, rather than the shoulder 3 or ledge I55.

The operation of the velocity controlled slide for automatically shifting the reversing mechanism of the jack into load raising position will now be described. Mention was made above of the fact that when the pedal I20a (Figure 1) is depressed, the locking arm I I6 is swung forwardly, carrying with it the slide I25 until the latch projection I is engaged against the shoulder I32 on the slide I25. This puts the spring I28 45 under compression. During normal manual operation in lowering the load under the control of the handle 53, the segment I0 is oscillated back and forth, the control of the reversing cam I02 serving to permit the lifting pawl 82 to take up the load on the ratchet wheel 50 and lower the same a certain distance, at which time the holding pawl 90 takes care of the load while the lifting pawl 32 is advanced to a new position. During this oscillatory movement of the segment I0, the lug I50 will engage the arm I43 and swing the weighted latch lever I40 partly out of engagement with the slide I25. This position is shown in Figure 9, and from this figure it will be noted that the projection I45 has been moved 69 to a point on the shouldered section I32 such that a relatively small additional amount of force is all that is required to completely carry the latch out of engagement with the slide I25. However, during normal manual operation, the movement of the handle is slow enough so that the latch is not completely disengaged from the slide, and if there is any tendency for the latch I40 to remain in the position shown in Figure 9, the subsequent back stroke of the segment will fully reengage 70 the latch I40 with the slide I25 by virtue of the engagement of the lower lug or lobe I5I with the end of the arm I43, the lugs I50 and I5I being spaced apart so that the last portion of the lowering movement of the segment "I0 will be just sufficient to reengage the latch I40. This is the position shown in Figure 8. The reengaging movement imparted to the latch I40 by the lower lug I5I positively raises the end of the arm I43 so that its engagement by the upper lug or lobe I50 upon the completion of the next raising stroke of the lifting handle and the oscillatory segment 10 is ensured. 7

Figure 9 discloses the oscillatory segment at its 'limit of upward travel, and it will be observed that the latch member I40,'which has been moved by the lug I50 to the position shown in this figure, is not entirely out of engagement with the slide I25, although it has been moved to the position where a relatively small additional amount of movement will serve to free the latch from the slide. The purposeof the weighted portion I44 of the latch I40 is to supply this additional energy for releasing the slide I25 when and if the velocity of the lifting handle and segment. For

example, if during the lowering of a heavy load the operator loses his grasp on the handle, the reaction of the load, acting through the ratchet mechanism, will swing the handle upwardly with considerable force. The parts are so adjusted, in the preferred form of construction, that the energy imparted to the latch lever I40 is sufficient to carry the same entirely out of engagement with the slide I25, in which case the biased spring I28 is then effective to snap the slide to the right as viewed in Figure 9, thereby swinging the reverse locking arm H8 to the position shown in Figure .6 and forcing the cam plate I02 back toits raising position, which allows both pawls to contact with the ratchet wheel 50. For this purpose the spring 5233 is of greater strength than the spring I08. Since the jack is then adjusted for raising the load, this automatically stops further handle movement and places the jack in raising position. To start lowering again, it is necessary to 'step on or depress the foot pedal so as to again place the slide I25 in biased position to the position shown in Figure 8.

' The weight of the latch lever I 40 and the distance through which the lug I50 positively moves the same before the arms H of the oscillating segment 18 engage the edge I56 of the housing 2 are the principal factors governing the sensitiveness of the latch I 40 to the velocity of the oscillating segment. For example, the present invention contemplates the provision of a jack in which no automatic lowering of the load is permitted, no matter how light. On the other hand, the present invention also contemplates the provision of a jack in which the latch parts and associated devices are so constructed and adjusted that the automatic lowering of relatively light loads is,permitted.where the oscillations of thelifting handle may not be'dangerous. However, in mechanical jacks automatic downward ratcheting of even relatively light loads may introduce undesirable impact stresses, and

therefore the rapid oscillations of the handle may take on dangerous aspects and should not be permitted under such conditions. 1 v

Under some conditions, it may be possible to I give the oscillatory segment 10 more room for upward movement, in which case dangerous or undesirable velocities of the lifting handle" will positively throw the latch I40 entirely out of engagement with the slide I25 without relying on the inertia of the latch to complete the release. Also,the latch I40 may be so designed that the spring I28 itself will serve to positively return the latch to the position shown in Figure 8 after a momentary depression of the lever I40 to the position shown in Figure 9 by the manual ralsing of the lifting handle, and in such case the lower lug I5I can be eliminated if desired. The present invention also contemplates a construction in which the latching lever I40 is not moved relative to the slide at any time unless the velocity of the handle becomes excessive. forms fall within the scope of the present invention. I

The above described biased slide, which is normally latched in the position shown in Figure 8 to automatically throw the jack into raising position when the oscillations of the lifting handle and associated parts become excessive, is obviously only one of a number of different means for providing a jack which is safe to use under all conditions. In Figure 11 I have shown a device, operating upon hydraulic principles, for automatically terminating operation of the jack when there is a tendency for the load to ratchet itself downwardly by the oscillation of the lifting handle at dangerous or undesirable velocities. Referring now to Figure 11, as well as to Figure 2, it will be observed that a cylinder I10 is provided with a closed end I1I. which is pivoted onto the shaft 8| carrying thelifting pawl 82 and which, in turn, is carried at the lower ends of the segment arms H. The hydraulic cylinder I10 is fitted with a piston I13 with a certain clearance between the piston and the walls of the cylinder, and the piston I13 is carried by a piston rod I 14 pivoted, as at I15, to a boss I16 carried in the lower section of the ratchet housing 2. The piston rod I14 is packed by means of a suitable packing follower I80 and packing All of these j sleeve IBI filled with suitable packing material and a counterbore I86 by which 'flow of'llquid from one side of the piston to the other'in the cylinder I10 is permitted. The bore I85 is controlled by a spring backed ball I88 held in the counterbore I90 by means of a pin I 9I or other suitable means. The ball I88 is yieldingly retained by its spring I92 in a position clear of its tapered seat I83 where the bore I85 joins the counterbore I88, so that the free flow of fluid from one side of the piston to the other is not materially restricted, but if there is a too rapid flow of oil in through the bore I85 from in front of the piston to the other side of the piston, the ball I88 is pressed against its seat I93, so that at this time the only passageway for the liquid from in front of the piston is through the clear. ance between the piston and the walls of the cylinder, which is relatively small.

Since the cylinder I10 is connected with the oscillating segment 10, the cylinder and piston have relative movement with the raising and lowering movements of the lifting handle 53. As the handle 53 is raised the liquid in the bottom of the cylinder I10 is forced past the ball I88 and through the bores I85 and I86 to the other end of the cylinder. Under normal manual operation of the jack the oscillations of the segment 1B are relatively slow so that the spring holds the ball 288 off its seat, and the movement of the segment is not materially restricted. If, however, the operator loses his hold on the handle, permitting the weight on the jack to throw the handle upwardly with increased velocity, the pressure on the right hand side of the piston 113, as viewed in Figure 11, materially increases so that the pressure of the liquid moves the ball I88 against the tension of its spring and closes the opening I85, thus checking the speed of the handle to such an extent that further travel at any appreciable velocity is prevented. The weight on the jack causes the lifting handle 53 under these conditions to move toward its upper position, but such movement will be relatively slow and will not be at any undesirable velocity. The hydraulic check may be so constructed and arranged that all automatic downward ratcheting of the load is prevented or, if desired, relatively light loads may be permitted to lower themselves, particularly since the operation of the jack mechanism is cushioned by the hydraulic check.

This is an important feature of the present invention. The spring backed ball I88 is so arranged that an increase in pressure thereon, as from acceleration of the upward movement of the segment '56, closes the opening I85, as mentioned above, and the clearance between the piston and cylinder is such that the resistance to the acceleration of the upward movement of the lifting handle is increased at a greater rate, by virtue of the restriction to fluid flow, than the pressure in the cylinder is increased by the aforesaid acceleration on the handle. Not only does this effectively prevent the upward movement of the handle with sufficient velocity to cause the load to automatically lower itself, since the velocity of the handle is not sufficient to reverse the pawls, but the normal ratcheting of the jack is effectively cushioned.

This operation is also important from another standpoint. The impact of the lifting handle upon reaching its extent of upward movement is thus effectively cushioned, thereby preventing the handle rebounding with sufficient velocity to engage the ratchet gear and momentarily raise the load to raise the holding pawl. By checking the upward travel of the handle, there is substantially no impact at the end of the upper stroke, and consequently there is not suflicient force left to continue the cycle of operation. As a result, the handle automatically comes to rest at the upper limit of its travel. In this form, however, it is to be remembered that the operating ratchet mechanism of the jack is left in lowering position, so that all that it is necessary to do to continue the lowering of the load is to operate the handle 53 in the normal manner.

The hydraulic check, the operation of which in connection with preventing the automatic lowering of the load under the reaction of the weight thereof has just been described, has other important operating characteristics. The hydraulic check device serves as a means for automatically preventing undesired velocities from being imparted to the lifting handle. By undesirable velocities is meant any sudden acceleration of the handle for any reason whatsoever. Acceleration of the handle and oscillating segment under the reaction of the weight of the load has been referred to above in connection with the operation of these reactions in allowing the load to automatically ratchet itself downwardly. Sudden acceleration of these parts may occur for other reasons. For example, during the lowering of the load when the lifting handle has been swung to the position shown in Figure 4, the lifting pawl picks up the weight of the load on the ratchet wheel, and the holding pawl is released. The sudden imposition of the weight of the load on the lifting pawl may tend to jerk the handle, and in some cases this may be sufficient tojerk the handle out of the grasp of the operator. Similarly, at the limit of the upper travel of the handle during the lowering operation, the load is transferred from the lifting pawl to the holding pawl and, if the handle is moving upwardly at considerable velocity, the transfer will be made suddenly and with consequent racking of the jack. By the provision of a hydraulic check, the velocity of the oscillations of the jack mechanism is kept down to a desirable minimum so that the operation of the jack is cushioned at all times. Even during the raising operation, the transfer of the load reaction from one pawl to the other is made smoothly and easily because the hydraulic check is instantly available to restrain any sudden acceleration of the jack mechanisin.

For rapidly elevating the saddle upwardly into engagement with the load and to eliminate the necessity for slowly elevating the saddle by the handle 53 during the time prior to its engagement with the load, one end of the pinion shaft 49 is extended, as best shown in Figure 5, outside the casing 2, and has mounted thereon a pedalactuated speed-up mechanism I59 like that shown in the copending application referred to above. No claim is made herein to any details per se of such speed-up mechanism, and hence a complete description is unnecessary. It is sufficient to note that the speed-up mechanism includes a member 200 mounted for oscillation on one end of the shaft 49 and adapted to cooperate with a pinion or toothed wheel 206 to rotate the shaft 49 at a rate greater than the rate at which it can be actuated by the handle 53. For a complete description of the speed-up mechanism, reference may be had to the aforesaid copending application.

While I have described above the preferred construction, it is to be understood that my invention is not to be limited to the specific details shown and described, but that, in fact, widely different means may be employed in the practice of the broader aspects of my invention.

What I claim, therefore, and desire to secure by Letters Patent is:--

1. A jack comprising a lifting arm, a pair of side frames on which said arm is movably mounted, mechanism for operating said arm, a housing for said mechanism, and means including members acting in tension to securely hold one end of each of said side frames in abutment with said housing.

2. A jack comprising raising and lowering mechanism, means for operating said mecha-v nism, and means responsive to a rate of move ment of said operating means in excess of a given rate for automatically checking the further movement of said operating means.

3. A jack comprising lifting mechanism, means for raising and lowering said mechanism and ineluding a swin able handle and reversible ratchet means arranged, under loadjto provide for automatic lowering of said load, and means responsive to the velocity of said handle for preventing the continuance of the automatic lowering operahandle being swingable under certain load con-V ditions and energized by the load on the jack for automatically permitting the load to lower, and means responsive to the velocityof said handle and acting under the descent of a load heavy enough to cause said swinging handle to have an excessive velocity for checking the velocity of the handle and terminating the automatic descent of said load.

5. A jack comprising a frame, lifting means movably mounted on said frame, means for raising and lowering said lifting means, said means comprising ratchet mechanism and an oscillatory handle mounted on the frame and oscillatable during the raising and lowering operations, and means responsive to the rate of movement of said handle and associated parts for imposing a variable restraint upon the movement thereof to and means responsive to the rate of movement of said ratchet devices for opposing the movement in proportion to the velocity thereof, whereby said handle means is relieved of sudden shocks imposed on said ratchet devices.

7. A jack comprising a frame, lifting means movably carriedrthereby, means for raising and lowering said means including a ratchet wheel rotatably mounted on said frame, a swingably mounted member having alifting pawl cooperating with said ratchet wheel for moving the same, holding pawl means cooperating with said ratchet wheel for preventing backward rotationthereof, handle means connected with said swingably mounted member for. swinging the same, and reversing means cooperating with said pawl and said pawl means to provide for lowering the load on said lifting means by the operation of said handle, the reaction of said load being alternately imposed on said holding pawl means and said lifting pawl, both in the lifting and lowering operations, and a hydraulic check connected with said swingably mounted member and arranged to provide substantially unrestrained movement thereof below a given'velocity-and to oppose movement of said member when the reaction of said load tends to swing said member rotatably mounted on said frame, a swingably mounted member having a lifting pawl cooperating with said ratchet wheel for moving the same, holding pawl means cooperating with said ratchet wheel for preventing backward rotation thereof, 5

handle means connected with said swingably mounted member for swinging the same, and reversing means cooperating with said pawl and said pawl means to provide for lowering the load on said lifting means by the operation of said 1 handle, the reaction of said load beingalternately imposed on said holding pawl means and said lifting pawl, both in the lifting and lowering operations, and a hydraulic check connected with said swingably mounted member and arranged to 15 cushion the movement thereof and of the associated handle when the reaction of the load on said lifting means is alternately transferred from said lifting pawl to said pawl means and vice versa. o

9. A jack comprising lifting mechanism, means for raising and lowering said mechanism including a lifting handle adapted to be manually operated in both the lifting and the lowering operation, and a hydraulic check connected with said handle to oppose the movement thereof above a given rate, said hydraulic check com-' prising a piston and cylinder construction and valved by-pass conduits including a biased valve operative to reduce the effective area of the by- 3 pass in response to increased pressure in the cylinder following an acceleration in the rate of movement of said handle, said biased valve being adapted to permit said handle to move at a noninjurious rate. a 10. A jack comprising means engageable with a load for raising and lowering the same, mechanism for operating said means, said mechanism being adapted for manual operation and including automatically reversible controlling devices, 40 and means responsive to the rate of operation of said mechanism during the lowering operation for shifting said devices into raising position upon the occurrence of an excessive rate 'of operation of said mechanism. 11. A jack comprising means engageable with a load to be raised for lifting the same, means including pawl and ratchet mechanism for raising said load lifting means and including a' manually operable handle oscillatable to progressive- 5'0 a load to be raised for lifting the same, pawl and c0 4 ratchet mechanism for operating said means and" including a swingable handle and'pawls for advancing said mechanism and holding the same in advanced position, cam means cooperating with said pawls in one position to permit the load to be raised and in another position to permit the load to be lowered, means for shifting' said cam means from one position to another, and means responsive to an excessive rate of movement of said handle for automatically shifting said cam means to load raising position.

13. A jack comprising a frame, means en-' gageable with a load for raising the same, mechanism for operating said means, including a ratchet, swingable handle means mounted on the 7 frame, and cooperating pawls for operating the ratchet and holding the same against movement in one direction, an automatically shiitable reversing device cooperating with said pawls for permitting said load to be lowered under the control of said handle, a spring biased member adapted to shift said reversing device into load raising re lation, and means responsive to the rate of operation of said handle for releasing said biased member upon the occurrence of ex-' cessive rate of movement of the handle to shift said reversing device into load raising relation.

14. A jack comprising a frame, means engageable with the load to be raised for lifting said load, means mounted on said frame for operating said lifting means and comprising a manually operable handle swingably mounted on said frame, ratchet mechanism for operating said lifting means and including a pawl carrying member engageable by the handle for advancing the ratchet, and a holding pawl for holding the ratchet against movement in one direction, a biased reversing device shiftable under the influence of said bias into one position to permit the lowering of the load under the control of said handle, means for shifting said reversing device against said bias to provide for raising the load by the operation of said handle, a biased member cooperating with said last named means for shifting the reversing device against its bias into load raising relation, latch means engageable with said biased member for retaining the same in inoperative position when said shiftable means has been operated to release the reversing device to permit the load to lower, and means subjected to the impact of said pawl carrying member for releasing said latch, whereby said biased member restores said reversing device to 'load raising position upon the occurrence of an excessive rate of movement of said handle.

15. A jack comprising a frame, means engageable with the load to be raised for lifting said load, means mounted on said frame for operating said lifting means and comprising a manually operable handle swingably mounted on said frame, ratchet mechanism for operating said lifting means and including a pawl carrying member engageable by the handle for advancing the ratchet, and a holding pawl for holding the ratchet against movement in one direction, a biased reversing device shiftable under the influence of said bias into one position to permit the lowering of the load under the control of said handle, means for shifting said reversing device against said bias to provide for raising the load by the operation of said handle, a biased member cooperating with said last named means for shifting the reversing device against its bias into load raising relation, means for shifting said last named member into biased position when the 5 reversing device is shifted into said one position to lower the load, a weighted latch lever engageable with said last named member in biased position for retaining the same in position against said bias, and means fixedly connected with said 10 weighted latch lever and disposed so as to be subjected to the impact of said pawl carrying member, whereby upon the occurrence of an excessive rate of movement of said handle, the impact of said pawl carrying member on said weighted 15 lever causes the latter to acquire sufficient inertia to release said biased member and restore said reversing device to load raising position.

16. A jack comprising a frame, a lifting lever movably carried thereby, means for raising and 20 lowering said lever, and means reacting against said frame for limiting the extent of movement of said lifting lever in both directions.

17. A jack comprising a frame, a lifting lever movably carried thereby, a load supporting saddle 25 pivotally connected with said lever, link meanspivotally connected with said frame and with said saddle member for retaining the latter in horizontal position, and cooperating means formed on the outer end of said lifting lever and 80 on the adjacent portion of said saddle member for limiting the upward movement of said lifting lever.

18. A jack comprising lifting mechanism.

means including an operating handle and auto- 5 matically reversible ratchet means for operating said mechanism, and means responsive to an excessive rate of movement of said handle and associated parts during the lowering operation for checking the movement of said operating means. 40 19. A jack comprising raising and lowering mechanism, means for operating said mechanism including oscillatory parts and automatically reversible controlling means, whereby said operating means is automatically actuable under 45 certain load conditions and energized by the weight of the load on the jack for automatically permitting the load thereon to lower, and means responsive to the rate of movement of said operating means, when acting under the descent of a load heavy enough to cause said operating means to be actuated at an excessive velocity, for checking the rate of movement of said operating means.

EDWARD M. PFAUSER.

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