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 TM 55-1905-217-34
(1) Parts Identification. During disassembly, particular attention should be given to identification of parts for
reassembly. Spools are selectively fitted to valve bodies and must be returned to the same bodies from which they
were removed. Valve sections should be reassembled in the same order. If hand levers are used, remove the "E"
rings which retain the fulcrum rod and remove the links, levers and retaining rings.
(2) Attaching parts. Remove the four tie studs and nuts and separate the valve sections. Be careful not to
destroy or lose spacers.
(3) End caps. Remove the two screws which secure the spool and cap and remove the cap. Remove the
preformed packing from the body.
(4) Operating spool. Slide the spool out of its bore from the cap end and remove the preformed packing from
the valve body around the spool bore. Do not remove the centering spring and retainers unless it is necessary to
replace them.
(5) Check valve. Grip the stem of the check valve plug with pliers and pull it out of the valve body. Remove the
preformed packing and backup ring. Remove the spring and poppet from the valve body.
(6) Relief valve sub-assembly. Screw out the plug which retains the relief valve and remove the preformed
packing from the plug. Remove the spring and the relief valve sub-assembly.
(7) Valve body. Remove the plug and preformed packing from the blocked cylinder port on models with a
single acting spool. If the alternate discharge port is plugged, it is not necessary to remove the plug unless the body is
to be replaced.
d. Cleaning, Inspection, and Repair.
(1) Discard all old seals. Wash all parts in a clean mineral oil solvent and place them on a clean surface for
inspection.
(2) Carefully remove burrs by light stoning or lapping. Be certain there is no paint or burrs on mating surfaces of
valve bodies.
(3) Inspect the valve spools and bores for burrs and scoring. If scoring is not deep enough to cause
objectionable leakage, the surfaces can be stoned or polished with crocus cloth. If scoring is excessive, the valve body
and spool must be replaced by ordering a new section. Check the valve spool for freedom of movement in the bore.
(4) Check the relief valve for smooth movement in its bore. The valve should move from its own weight.
e. Reassembly.
NOTE
Coat all parts with clean hydraulic oil to facilitate reassembly and provide initial
lubrication. Petroleum jelly can be used to hold seal rings in place on assembly.
(1) Valve body. On models with single- acting spool, install the preformed packing on the port plug and plug the
appropriate cylinder port. Tighten the plug securely, but DO NOT over tighten.
(2) Relief valve. Install the preformed packing on the relief valve plug. Place the relief valve assembly in its
bore, hex nut ends towards opening. Install the spring and plug and tighten the plug securely but DO NOT over tighten.
(3) Check valve. Install a new back-up ring and preformed packing on the check valve plug with the preformed
packing toward the spring and poppet. Place the poppet and spring in the body and install the plug.
(4) Operating spool. If centering spring and spool have been removed, install new preformed packing in the
preformed packing groove in the body at each end of the spool bore. Install spool in bore from the cap end. Install the
flat retainer, guide and screw. Tighten the screw securely. Aline the flat retainer by shifting the spool. Spool bind is an
indication of flat retainer misalignment. Install the end cap and attaching screws. Tighten the end cap screws securely.
(5) Assembly of unit sections.
CAUTION
Make sure all mating surfaces of valve bodies are free of burrs and paint.
Install seal rings in the grooves in the body of each inlet and center section. Use petroleum jelly to hold the seals
in place. For CM2 valves, install the spacers to insure against spool bind when the studs are tightened. With the
mounting feet on a flat surface carefully place the sections together in the same order in which they were removed.
The mounting feet must be maintained in a flat plane to prevent spool bind (due to body distortion) when the valve is
mounted for operation. If levers are used, install pins in each spool and assemble the levers, fulcrum rod and "E" rings.
Tighten nuts on CM 2 to 45-50 foot pounds torque and on the CM 3 to 55-60 foot pounds torque.
f. Installation. Install the control valve (TM55-1905-217-12, para 4-89).
4-20. Ramp Hoist Counterbalance Valves
a. General. Landing craft with hull number 8500 thru 8519 have a Double A SA2-185-B-ITK44 counterbalance
valve and those with hull no. 8520 thru 8560 and 8580 thru 8618 have a similar valve Double A SA2-185D11/4 inches.
The major difference is in the relief pressure provided. Figure 4-49 illustrates both valves.
4-78
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