USE/CARE OF HANDTOOLS & MEASURING TOOLS - OD1621 - LESSON 2/TASK 1
different contracted and extended heights.
Another type of screw jack is
called an outrigger jack.
It is equipped with end fittings which permit
pulling parts together or pushing them apart and has a capacity of 10 tons.
(2) Ratchet Lever Jacks. A vertical ratchet lever jack (figure 48 on
the following page) has a rack bar that is raised or lowered through a
ratchet lever. Some of these jacks are equipped with a double socket; one
for lowering, one for raising.
Others have one socket as well as an
automatic lowering feature.
An outrigger ratchet jack is ratchet-operated
and has an extra reverse ratchet handle and a base plate.
(3) Vertical Hydraulic Jacks.
A hydraulic jack (figure 49 on the
following page) operates through pressure applied to one side of a hydraulic
cylinder which moves the jack head. These jacks are automatically lowered
in a variety of types, in capacities from 3 to 100 tons, having different
A push-pull hydraulic jack (figure
49) consists of a pump and ram connected by a hydraulic or oil hose. These
jacks are rated at 3, 7, 20, 30, and 100 ton capacities and have diversified
c. Using Jacks.
(1) Lifting Vehicles.
Vertical jacks are used to lift one side or
the end of a vehicle to permit removal of the wheel or tires, or to effect
repairs that would not be possible with the vehicle standing on its wheels.
The jack can be used on each side alternately by jacking up one side of the
vehicle, blocking it, and moving the jack to the other side, continuing this
operation until the vehicle has been raised to the desired height.
(2) Miscellaneous Lifting. The jack can also be used to raise heavy
crates, small buildings, or other items too heavy to be raised by prying
with wrecking bars. It is essential that the jack be placed on solid ground
or on a plank to spread the weight so that it will not give way or tip when