T M 55-1730-221-12
b. Non-critical structural areas of the base assembly
(56) may be welded, after it is certain that machined
a d j u s t by-pass valve in valve assembly (14) as follows:
areas will be unaffected by the welding. Cracks or
breaks at cylindrical machined surfaces necessitate
replacement of base assembly. Before attempting to
a. Ascertain that the reservoir is filled with fluid,
weld any portion of base assembly, wash, flush and
a n d that jack is in operating condition (refer to para-
thoroughly drain fluid passages and reservoir with a
b. Using the test stand, apply an 11 ton load to the
jack. Operate handle (1) to lift the load. Third-stage
ram (44) shall extend partially. If lift ceases, remove
screw (22), rotate screw (15) slightly clockwise, re-
p l a c e screw (22) and attempt to lift load. If necessary,
All weld repairs shall be performed in a
r e p e a t clockwise adjustment of screw (15) until partial
lift of third-stage ram is permitted with the 11 ton
defective parts other than reparable valve body (21)
seats and base assembly (56) shall be replaced (refer
to paragraphs 3-7a, 3-7b and to "REMEDY" column
of Figure 2-2).
If handle fails to "drop" or "go soft" with
c o n t i n u e d pumping at full ram extension, cease
3-9. LUBRICATION PRIOR TO REASSEMBLY. (See
Serious injury may
figure 3-1.) Prior to reassembly, dip all parts except
result because of excessively high by-pass
handle (1), pins (3, 4, 6, 7), links (2), lever (5), head of
pressure and sudden collapse of load.
p i s t o n (8), and external surfaces of base assembly (56)
in hydraulic oil, Specification MIL-O-5606. Lightly
coat pins (4, 7) with oil, Specification MIL-L-7870.
If excessively high pressure adjustment is evidenced,
screw (15) shall be adjusted slightly counterclock-
P r o t e c t oiled surfaces from dust accumulation pending
wise until by-pass valve is operative when pumping
is continued at 11 ton load with third-stage ram par-
the jack in reverse order of disassembly, noting the
c. Allow jack to remain with the third-stage ram
partially extended and increase load from 11 tons to
a . Install packing retainer (43) and packing (47) onto
1 1 - 1 / 2 t o n s . S c r e w (15) shall be set so that the next
pumping stroke of handle (1) will operate by-pass
third-stage ram (44). Work retainer and packing into
place between rams by manually pressing against
v a l v e , causing handle to "drop" or "go soft".
packing at several points.
b . After retainer (48) and packing (47) have been pro-
perly seated, install bearing (46), rapping lightly at
An exact adjustment setting to a maximum
lower edge of bearing with a soft-head mallet until
lift load (with by-pass functioning) of 11 tons
s e a t e d , and install retaining ring (45) on lower end of
is often difficult. Therefore a safety tolerance
Insert third-stage ram into
third-stage ram (44).
of plus 1 ton is allowable (12 ton maximum
second-stage ram (39) until ring (38) groove is ac-
However, whenever possible, the 11
cessible. Install ring (38).
t o n limit setting shall be observed.
c . Repeat procedure outlined in paragraphs 3-10a and
3-10b for second-stage ram (39) and first-stage ram
(33) and associated parts.
3-1.) After reassembly and by-pass valve adjustment,
test the jack as outlined in paragraphs 3-13 through
d. Install valve assembly (14) with gaskets (13) in
b a s e assembly (56) so that screw (15) hole is aligned
with screw (22) hole in base assembly. Maintain
3 - 1 3 . FUNCTIONAL TEST. Operate handle (1) with no
h o l e alignment with a wood dowel, and screw cylinder
l o a d applied to jack until rams (33, 39, 44) have ex-
( 1 2 ) into base assembly snugly, securing valve assem-
tended thirteen inches. Action of handle shall feel
solid at each pressure (downward) stroke.
e . After reassembling the jack, conduct by-pass valve
release valve (25) and collapse rams with an 80-
adjustment as outlined in paragraphs 3-11a through
Rams shall collapse flush under this