ARMY TM 9-2815-259-24
AIR FORCE TO 38G1-125-2
MARINE CORPS 09249A/09246A-24
(19) Measure the roller to roller dimension (Figure 5-40) by performing the following:
Secure roller-to-roller setting fixture (19969) in vise and insert rotor assembly. Connect
dry, clean, filtered, compressed air source regulated to 40-100 p.s.i. (4.5-11.3 kPa) to force
plungers outward until shoes contact leaf spring.
Using a 1-2 inch micrometer, measure the distance between the outer surfaces of each pair
of opposed rollers. Compare the dimensions to the roller-to-roller dimension called for on
the individual specification. Turn leaf spring adjusting screws clockwise to increase or
counterclockwise to decrease the dimension. The two dimensions must be within 0.0003
inches (0.076 mm) of each other and the average of both roller-to-roller dimensions must be
within 0.0015 of the specified dimension.
Example: Specified roller-to-roller dimension = 1.960 inches (49.78 mm). One pair of
rollers measures 1.961 inches (49.81 mm) while the other measures 1.958 inches (49.73
mm). The 2 dimensions are within .003 inches of each other and the average of the 2
dimensions (1.9595 inches) is within 0.0015 inches of the specified roller-to-roller. Since
each leaf spring controls one shoe and roller of each set it may be necessary to interchange
shoes between slots or use optical size shoes (as indicated on the specification) in order to
achieve the proper roller-to-roller dimension and concentricity.
After the roller-to-roller dimensions are achieved, the roller concentricity must be checked.
Proper concentricity is needed to ensure that all rollers strike the cam lobes at the same time
during pump operation.
Rotate the rotor until one roller is aligned with in dial indicator plunger on fixture 19969.
Slide the indicator inward until plunger depresses at least 0.010 inches (0.254 mm). "Zero"
indicator by loosening thumbscrew and rotating dial. Recheck "zero" by rotating rotor to be
sure indicator plunger is on high point of cam roller.
Rotate rotor and observe dial indicator reading for each of the other rollers. Roller
concentricity must be within 0.004 inches (0.1 mm). If not within specification,
concentricity can be achieved through interchanging of shoes or leaf spring positions.
FIGURE 5-40. MEASURING ROLLER TO ROLLER DIMENSION