US1518490A - Compound screw jack - Google Patents

Description

Dec. 9, 1924. 1,518,490

R. M. DIXON COMPOUND S CREW JACK Filed March 20, 192,@

/NVENTR BY Q Patentedl Dec. 9, 1924.

luNrri-:D STATES PATENT thai RANDALL M. DIXON, OIF STOCKTON, CALIFORNIA.

coMroUNn SCREW Jack.

Application led March 20, 1924. Serial No. 700,516.

part f this application.

This invention relates to improvements in lifting jacks, my main object being to provide a jack of the above named general char-v acter so constructed that a very powerful raising eect will be had, and loads may be lifted vthrough 'a considerable distance, while v at the same time the jack when its parts are fully contracted, will occupy `but relatively little vertical space.

While my jack may of course be used for any purpose for whichsuch an implement is suitable, I have particularly designed it for automobile service.

Automobiles must frequently be jacked up, usually to raise an axle so that a tire may be removed and replaced following a ypuncture or blowout.

In such` cases, and especially when the wheels are equipped withvthe oversize or balloon tires now coming into vogue, the axle will be lowered a considerable distance when such a tire loses its air and becomes flat.' Under such conditions, very frequently the ordinary small jacks if short enough when contracted to fit between the ground and axle, have not the liftingvrange necessary to raise the axle the required'distance,

'or if they have such lifting range, they are too tall evenwhen fully telescoped or contracted, to ,fit under the axle when the tire is flat. n

The result is that the operator must resort to various time-taking and laborious expedients in order to be able to jack uphis car. e

M improved jack eliminates the above trou les, by having asbefore stated, a great'.

range of lift coupled with an extremely compact or short size when contracted.

A further object of the invention is to produce a sim le and inexpensive device and yet one whlch willbe exceedin ly effectivefor the purpose for which it is designed.

These objects I accomplishiby means of 21 proj ectin such structure and relative arrangement of parts as will fully appear by a perusal of the 'following specification and claims.

In the drawings similar\ characters of reference indicate corresponding parts in the several views: f*

Fig. 1 is a vertical section of the jack with the lifting members partly raised.

Fig. 2 is an exterior elevation of the jack `in its fully contracted form.

Fig. 3 is a cross section on the` line 3 3 of Fig. 1.

Referring now more particularly to the characters of reference marked thereon, the numeral l denotes a vertical cylindrical casing or pedestal, mounted in the lower end of which is a base pad 2. Turnably mounted on said pad is a bevel gear 3 meshing with a pinion 4 whose'shaft or spindle 5 is journaled in a bearing boss 6 formed with thecasing 1. The shaft 5 slopes up at a certain angle, and is bored with a square hole as at 7 or in an manner to non-turnably receive a pin on telower end of a ratchet turning handle or lever of any suitable form. The outer end of the member 5 is preferably provided with a knurled collar 8, whereby the pinion may be turned by hand if desired.

The gear 3 has a hollow shaft9 mounted therewith and projecting upwardly into the casing for a certain distance and concentric therewith.

This shaft has longitudinal splines 10 on its outer periphery which engage and slide in splineways- 11 4cut in the bore of a tubular sleeve 12. This sleeve is exteriorly threaded throughout" its length with left hand and preferabl square threads 13 of 'a certain pitch, whic engage with cooperating threads 14 cut in the bore of the casing for a certain distance downwardly from the upper end thereof.

In the upper end of the bore of the sleeve 12 are cut rlght hand threads 15, also preferably square, which cooperate with similar threads 16 cut 'for the full length of astem 17, the bore of the gear-shaft 9 being of a size tp freely receive said stem therein.

On the upper end of the stem is a fixed pad 18 of suitable size and design. Another pad 19 is adapted to rest on the pad 18, being hinged as at 2O to a transverse member j radially under and beyond the pad 18. n this manner, the upper pad 19 may be swung down out of the way if its use isnot deslredhthus enabling the dis# los lll@

. itially setting thejack up to be used. t

22 depending downwardly therefrom and The member 21 projects beyond the pad 18 on the side thereof opposite the hinge 2O and has secured thereto a vertical stem slidable in a sleeve 23 guided by a horizontal boss 24 projecting from the upper end of the casing 1. The members 22 and 23 have outwardly and inwardly projecting shoulder dportions 25 at their lower and upper en s respectively, so that when the stem 22 has been raised a certain distance, its shoulder will engage the shoulder on the sleeve 23 and the latter will then, and not until then, be raised also. The purpose of this telescoping lstructure is to prevent `rotation of the jack stem 17.

In operation, if the pinion 4 is turned to the right, the gear 3 and member 12 will be turned in a clockwise direction. The member 12 being threaded into the casing with left hand threads, such rotation will cause the member 12 to be advanced from the casing. At the same time, the 'stem 17 being screwed into the sleeve 12 with threads oppositely cut to those on the outside of the sleeve, and being held against rotation, is likewise advanced from the sleeve 12 with the advancement ofthe latter from the casing. The different screw threads should be of such relative itchthat the lowerl end of the sleeve 12 reac es the lower end of the cooperatin threads in the casing at the same Vtime as t e lower end of the stem 17 reaches the lower end of the cooperating threading in the sleeve.

The distance that these members ma travel in the res ective members in Whic they are mounte being substantially equal, both the stem and sleeve should therefore advance the same distance for each revolution of the sleeve.

It willtherefore be seen that by reason of the telescopin members, the heig t to which the pad may be raised from the top of the casing is considerably greater than the total height of the casin itself. l

While le threads on the sleeve are specilied as left hand and those onthe stem 17 as ri ht hand, this is only because the pinion 4 1s presumed to be turned to the right to raise-the stem. If the pinion was intended to be turned in the opposite direction, or the gear was arran ed so as to turn counter# clockwise with t e turning of the pinion to feature of the raisingA the right, then the relative arrangement of 00 the threads on the sleeve and ,stem would be reversed.

From'the foregoing description it will be readily seen that I have roduced such a device as substantially ful) the invention, asv set forth herein.

While this specification sets forth in detail the present and preferred construction of the device, still in practice such deviations from such detail may be resorted to as do not form a departure from thespirit of the invention, as defined by the appended claims. v

Having thus described my invention what- I claim as new and useful and desire to sef cure by Letters llEatentis:

fills the objects ofA stem normally telescoped therein and capable of being projected therefrom,.a' rod fixed' to and extending parallel with the stem to move vertically therewith, a sleeve slidably mounted on the casing and arranged to remain stationary during the initial movement of the rod, and means whereby when the rod has moved a predetermined distance the sleeve will then be raised with any further movement of such rod.

2. A jack comprising a casing, a lifting stem normally telescoped therem and caipable of being projected therefrom, a rod Xed to and extending parallel with the stem to movevertically therewith, a sleeve slidably mounted on -the casing and arranged to remain stationary durlng the initial movement of the rod, the rod and sleeve having co-en aging shoulders on their upper and lower en s respectively whereby to cause them to move as a kunit after the rod has moved a predetermined distance.

3. The combination in a jack of the type described, havin a casing and a jack stem movable vertical y therethrough, of a guide means, such means including a sleeve mounted for vertical slidin `movement relative to the casin the bore .o the sleeve adjacent its f RANDALL M. DIXON.

of a diameter equal to that of the

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