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gear, which is keyed to the opposite end of the main shaft, to which is attached the lift chain wheel. Motion is transmitted from the hand chain to the lift chain, and by pulling on the hand chain, in either direction, the load is lifted or lowered. When hoisting a load the brake wheel, with its ratchet teeth on the
outer rim, rotates freely with the hand chain wheel and pinion, and without resistance, as the ratchet pawl runs freely over the teeth. When the pull on the chain wheel ceases, the pawl engages with the teeth of the ratchet on the brake wheel, preventing it from running backward, and so keeping the load suspended.
In lowering the load the hand chain is pulled in an opposite
direction, and but little effort is required to overcome the friction of the automatic brake, thus permitting the load to descend and holding the same suspended again, as soon as the workman stops pulling on the hand chain. The load can be lowered at a good rate of speed by a continuous pull upon the hand chain. By means of an ingenious arrangement of the lower block, the lift chain is locked to the chain wheel of the lower block, providing the two speeds referred to, making for economy of time in handling light loads. Closed rings attached to a swinging frame provide guides for the hand chain, enabling the operator to stand away from under a load, pulling the chain at an angle, without producing any appreciable amount of friction or wear on the chain or guide. The construction eliminates the possibility of the chain wedging between the wheels and guides.
In many shops it is inconvenient to provide pits by which the workmen may gain access to the under portions of an automobile. A very practical elevating device which provides plenty of space for working under a car is shown at Fig. 17, F and G. In the former illustration the front end is shown raised, while at G the rear end is elevated. This consists of a light, inclined runway made of planking and timbers upon which the car may be run. A pair of hollowed blocks at the upper portion in which the wheel tires fit provides a positive stop to prevent the car from rolling off the stand.
Another useful device for use on the assembling floor that saves considerable time when an entire end of a car is to be raised, as is necessary for inspecting parts of the steering system or rear axle faults, is shown at H. This is known as the Weaver twin jack, and consists of a triangular framework mounted on wheels and carrying two lifting screws actuated by bevel gears near the base of the triangular frame. A cross shaft carrying similar sized bevel gears actuates the lifting nuts on the vertical screws, and is in turn operated by a bevel gear turned by a pinion, to which motion is imparted by a hand crank. The gearing is so arranged that a large amount of leverage is provided and the heaviest car may be raised without any exertion. The hand crank is mounted in a swivelling bracket, which makes it
possible to operate the jack without stooping or to fold the handle over entirely out of the way. As the jack is carried on a wheeled frame, the car may be moved around even if the two wheels on the axle supported by the jack are removed.
A reader of “Motor Life” sends a description of a quick action lifting jack that is very well adapted for garage use, though too bulky to be included as part of an automobile equipment. This form has been widely used in connection with racing, as an entire front end of a car may be easily raised and held by the force exerted by one man at the end of the long lever when a quick tire change is necessary and where every second counts. The usual form of lifting jack operating on either the ratchet or lifting screw principle would require considerable time to raise the wheels clear off the ground, whereas the form depicted at Fig. 19, A, will do the work in 15 seconds.
This consists of a handle or lever, 8 or 10 feet long, supported and pivoted between two uprights attached to the base. Underneath the front end of the lever is a swinging post which supports the weight of the car when in a vertical position. The size of the parts and strength of the lever will vary with the weight of the
The base, uprights and handle may be of wood. The base should be about 20 inches long and 6 or 8 inches wide, having the uprights mortised into the sides and braced with blocks on the inside corners.
The uprights may be about 4 inches wide, both these and the base being of 1-inch material. The height of these uprights and length of the post will depend upon the diameter of the wheel and the amount it is to be raised. Supposing that the distance from the ground to the underside of the hub or axle is 151/2 inches and that the wheel is to be raised 3 inches, then, allowing 114 inches for the thickness of the base, the length of the post will be 171/4 inches minus the thickness of the lever under the wheel.
This post or support may be made either of wood or iron, and pivoted underneath the lever in any convenient manner so that it will swing freely. An iron rod with one end bent to form an eye may be obtained from any blacksmith shop for a few cents. A bearing may be formed for this rod either from wood
blocks or heavy sheet metal attached to the sides of the lever as shown. The holes in these blocks as well as the eye in the upper end of the post should be large enough to take a threequarter inch bolt. Another three-quarter inch bolt may be used to support the lever in the uprights. There will be considerable space between the sides of the post and the blocks, and this may
Fig. 19.—Quick Action Car Lifting Jacks and Truck for Use in Towing
be filled by using a number of three-quarter inch washers on the bolt. The same method may be used to fill the space between the lever and the two upright pieces.
On the top of the lever, directly above the support where the hub or axle rests, a shallow V-shaped groove should be cut so that the axle cannot slip off the jack when raised. The underside of each end of the base should be rounded off so that the jack can be slid over the floor of the garage without the corners catching on projections. The operation of raising the wheel is quite simple, since all that is necessary is to slip the jack under the hub or axle so that the weight will come directly in the groove above the support, when the car is raised by pressing down on the outer end of the lever. Since the supporting post swings freely it will assume a vertical position when the car is raised, so that when the weight is taken off the outer end of the lever the post takes the entire strain of the load. In order to facilitate removing the jack from the car, a small wire rope should be attached near the lower end of the post and run through a ring in the outer end of the lever. Thus when the lever is pressed down the post swings free and may be pulled back from under the wheels.
The jack is shown from two different viewpoints in illustration, but it seems hat the builder of this has not taken the fullest possible advantage of his opportunities. If, as he says, jacking up is slow and tedious work, the device as shown only eliminates the work of raising the car by means of the jack, and substitutes for it the task of prying up one wheel at a time, then putting blocks or some firm and stable object of the right height under the axle, next letting the jack down and moving to another wheel. With the device as constructed, it would take four different applications to lift a car entirely clear off the floor, two at the rear axle close to each wheel, and two at the front axle, near each wheel.
It is possible to reconstruct the jack as outlined so this work may be reduced to two applications, one for the rear axle and one for the front. This is done by constructing the jack about as outlined, but in duplicate, fastening the two together at the front end and also at the rear. In addition, it will be necessary to make the handle much longer and stouter, for whereas the former