REPLACEMENT.

T.O. 35A2-2-39-11

T M 55-1730-221-12

3-11. BY-PASS VALVE ADJUSTMENT. (See figure

b. Non-critical structural areas of the base assembly

3-1.) Using test stand described in paragraph 3-14,

(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

graph 2-2).

non-combustible solvent.

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

ventilated area.

lift of third-stage ram is permitted with the 11 ton

load.

3-8. REPLACEMENT. (See figure 3-1.) Damaged or

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

pumping immediately.

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

reassembly.

wise until by-pass valve is operative when pumping

is continued at 11 ton load with third-stage ram par-

3-10. REASSEMBLY. (See figure 3-1.) Reassemble

tially extended.

the jack in reverse order of disassembly, noting the

following:

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.

NOTE

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-

load) .

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

3-12. TESTING. AFTER REASSEMBLY. (See figure

(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

3-17.

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

bly.

solid at each pressure (downward) stroke.

Open

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

pound load.

Rams shall collapse flush under this

3-11c.

load.

3-4