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U 4.70-4.100
REPAIR & SERVICE
MANUAL
PAGE 3
The following procedure is required anytime a major component is replaced. (End shield, Rotor, or Cylinder)
1. Place cylinder housing on workbench so that the minimum clearance area (the area of minimum rotor to
cylinder clearance when the unit is fully assembled) is positioned on the bottom.
2. Remove locating pegs from both endshields. Mark endshields for suitable location of new holes for locating
pegs.
3. Using drill press, drill pilot holes in locations marked on endshields. Use # 16 drill bit for pilot holes. Be sure to
make pilot holes perpendicular to sealing surface of endshields.
4.
Insert gauge tape (feeler gauge, shim stock, paper, or non-reinforced plastic tape) of the proper thickness (see
table #1,rotor to cylinder clearance) and approximately the same width as a rotor segment (the area between two
vane slots) into the cylinder. Gauge tape should be about 1" shorter that the rotor and should support the rotor
above the cylinder.
5.
Install A-side endshield but do not fully tighten bolts.
6. Place rotor into cylinder housing making sure that a rotor segment and not a vane slot is resting on the gauge
tape.
7. Install B-side endshield but do not fully tighten bolts.
8. Using moderate pressure, press down and center endshield bolts in bolt holes, while pressing down tighten
endshield bolts. Repeat on opposite end.
9. On #9 drill bit mark drilling depth using locating peg as guide.
10. Using pilot holes drilled in step 3 drill endshields and body to proper depth. Be sure to keep drill perpendicular
to sealing surface of endshields.(Use drill press if needed.) Repeat on opposite end.
11. Clean holes with compressed air and install locating pegs.
12. Remove one endshield and rotor. Remove gauge tape.
13. Reinstall rotor and endshield.
14. Rotor to cylinder clearance is now reset, continue reassembling unit in normal manner.
TABLE #1
PUMP TYPE
ROTOR LENGTH
U 4/2.70
114.97-115.0
U 4/2.100
169.945-169.97
DRAWING # 1
U 4.000 ROTOR
Setting Rotor to Cylinder Clearance
HOUSING LENGTH
115.128-115.15
170.125-170.15
CYLINDER DIA
VANE LENGTH
122.0-122.04
114.75-.80
122.0-122.04
169.75-.80
ROTOR TO
CYLINDER
0.07 / F 0.05
0.07 / F 0.05
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