TM 5-3820-241-34
(b) If the holes i n t h e c r a n k s h a f t a r e
b. Inspection and Repair.
(1) Cylinder Compression Test.
enlarged, the crankshaft must be replaced. The
tramming motor cannot develop its rated horse-
(a) Place th e cylinder upside down on a
power if the porting in the rotary valve does not
bench and seal off the air port into the cylinder.
( b ) Remove the rings from the piston,
match the timing of the piston strokes.
then drop the piston into the cylinder. The piston
(5) Oil Seals and Bearings.
s h o u l d move slowly into the cylinder. If the
(a) Inspect the bearings for excessive
piston falls into the cylinder it is defective and
wear. Replace defective bearings.
must be replaced.
(b) Discard and replace all oil seals.
(2) Piston, Ring Gap.
( 6 ) Rotary Value. C h e c k t h e c l e a r a n c e
(a) Place one ring at a time in cylinder,
between the rotary valve and the valve bushing.
making sure it is not tilted.
When wear exceeds .010 inch, replace the housing
(b) Use a feeler gage and measure the ring
and bushing.
cap. If the gap exceeds .015 in. it is defective and
6-4. Tramming M o t o r Reassembly and In-
must be replaced.
stallation
( c ) Each new ring must also pass the
a. Reassembly.
above test. If the ring will not turn over in the
(1) Coat all p a r t s with a light film of oil
cylinder, file the gap slightly so the ring will turn
before reassembly.
over.
(2) Reassemble the tramming motor in the
NOTE
reverse of numerical sequence as illustrated in
A close cap clearance in air motors
presents no problem in air motors since
(3) Install the connecting rod retaining rings
there is no expansion of parts due to heat.
(26) and (30) with the chamfered side next to the
(3) Connecting Rod Bushing. Inspect the
connecting rod (27).
c o n n e c t i n g rod retaining rings for cracks or
b. Installation.
breaks. Replace rings if cracked.
(1) Install the tramming motor (para 2-14).
(4) Rotary Valve Drive Pins.
(2) Refer to LO 5-3820-241-12 and lubricate
(a) Check, the t h r e e drive pins on the
the rock drill.
crankshaft end of the rotary valve for a snug fit
into the holes of the crankshaft.
Section II.
TRAMMING
TRANSMISSION,
BRAKE AND CRAWLER DRIVE
6-5. General
(1) Remove the tramming motor (para 2-13).
(2) Remove the tramming transmission and
The tramming motor brake assembly is mounted
brake housing (para 2-17).
b e t w e e n the tramming motor and the trans-
b. Disassembly.
mission gear case. The brake is a deadman type
(1) Tramming Brake.
and when the tramming motor is off. The trans-
(a) Disassemble the tramming trans-
m i s s i o n is a planetary type with a 35:1 gear
mission brake in a numerical sequence as il-
reduction.
lustrated in figure 6-2.
6 - 6 . Tramming Transmission, Brake and
Crawler Drive Removal and Disassembly
a. Removal.