o.
Thread plunger (11) on a 2-1/2 inch long 20-14 NC screw. Insert the plunger into bore of cover and remove the
screw. Install the spring (10) and plug (8) in cover (9).
p.
Install drain plug (4), then remove fill plug (5) and fill the transmission with lubricant. Install plug (5).
4-14.3 Pulldown Transmission Control (Figure 4-37A).
4-14.3.1 Removal.
Remove the cotter pins (1) and yoke pins (2) to remove the shift tie rod assembly. Loosen the nuts (4); then
unscrew the adjustable yokes (3) from the tie rod (5). Remove bolt (6) and lockwasher (7) to remove the shifter
(8) from the transmission. Finally, remove cotter pin (9) to remove shifter handle (10).
4-14.3.2 Cleaning, Inspection and Repair.
Clean parts with an approved cleaning solvent and inspect for any damage or wear. Replace any damaged
parts.
4-14.3.3 Assembly.
Install the shifter handle (10) and secure it with the cotter pin (9). Install shifter (8) to the transmission shift shaft
and fasten it with capscrew (6) and lockwasher (7). Screw the nuts (4) onto the tie rod shaft (5); then screw on
the adjustable yokes (3). Before tightening the nuts, make sure the shift tie rod assembly is the correct length,
adjusting yokes as necessary. Then install the yoke pins (2) and cotter pins (1).
4-15 MAINTENANCE OF DISCHARGE PIPING ASSEMBLY
4-15.1 Shear Relief Valve. The shear relief valve relieves excessive pressure in the mud circulating system by shearing
the nail installed through stem. The relief pressure is determined by the size of nail used. Size to pressure are as
follows:
16 Penny relieves at 1000 lbs.
10 Penny relieves at 850 lbs.
8 Penny relieves at 650 lbs.
6 Penny relieves at 500 lbs.
4 Penny relieves at 400 lbs.
3 Penny relieves at 250 lbs.
CAUTION
Never install a hex key or any other high strength material in the shear nail hole. This usually
results in pump damage.
4-15.1.1 Resetting Valve.
a.
After relieving the blockage that has caused overpressure condition, push the guard (2, figure 4-38) down to
close relief valve.
4-159
