manually operated pumps. They have carrying handles,
pump handles, reservoir vent valves, release valves, and
safety valves. The different model sizes vary from 4 3/4
inches to 9 inches high (closed). Their weights vary
from 26 to 120 pounds.
HORSESHOE.--Horseshoe axle (fig. 1-27) or
crocodile jacks consist of a lifting arm supported by
two hydraulic cylinders. The cylinders move up over
the stationary pistons when the manual pump operates.
The A25-1HS is a large jack, 5 feet long, 5 feet 8 inches
wide, standing 2 feet 1 3/4 inches high, and weighing
900 pounds.
Figure 1-28.--T-Bar axle jack.
T-BAR.--The T-Bar or alligator axle jack (fig.
1-28) is mounted within a T-shaped frame. A manual
pressure pump and a speed pump mount on opposite
come from the jack placement on the aircraft. The
sides of the towbar end of the frame. The jack weighs
points for jacking vary with the type of aircraft, and can
235 pounds and is 4 feet 2 1/2 inches long, 2 feet 3
be found in the MIM for each type of aircraft.
inches wide, and 10 inches high (closed).
There are two different types of tripod jacks--fixed
OUTRIGGER.--This cantilever axle jack (fig.
height and variable height. Both are mobile,
1-29) is a very large and heavy jack. It weighs 2,190
self-contained, hydraulically operated units. They
pounds and is 7 feet 3 inches long, 6 feet 8 inches wide,
consist of three basic assemblies. These assemblies are
and 2 feet 3 inches high. A double (two-speed) pump
the hydraulic cylinder, the tubular steel wheel tripod leg
mounts on the left-hand side of the frame to operate the
structure, and the hydraulic pump. The main difference
hydraulic cylinder.
between the two types is that the tripod structure on a
variable height jack can be adjusted to different heights
Airframe (Tripod) Jacks
by adding leg extensions.
All model designations for tripod jacks begin with
Use airframe (tripod) jacks for lifting the entire
the letter T, for Tripod, such as T10-2FL or T20-1VH5.
aircraft off the ground or deck. Airframe jacks are
The number following the T indicates the jack capacity
commonly called tripod jacks. You may hear them
in tons, such as 10 for a 10-ton jack. This is followed by
called wing, nose, fuselage, or tail jacks. These names
a dash (-) and the specific jack identification number.
Then comes two letters indicating the type of tripod
jack (FH = fixed height, or VH = variable height). The
number that follows the VH for variable height jacks
indicates the number of leg extension kits available for
that jack. Figure 1-30 shows a T20-1VH5 jack with
Figure 1-29.--Outrigger axle jack.
Figure 1-27.--Horseshoe axle jack.
1-30
