Usage:
Air Lines (Choke)
(1) Aftercooler cover.
(2) Air inlet from turbocharger.
(3) Choke plate housing.
(4) Choke plate and shaft.
(5) Thrust washer.
Width of groove in shaft for thrust Washer ... 6.53 ± 0.10 mm (.257 ± .004 in)
Thickness of thrust washer ... 6.00 ± 0.05 mm (.236 ± .002 in)
(6) Choke plate lever.
(7) Cross shaft lever angle.
(8) Choke plate adjusting bolt and locking nut.
(9) Choke plate housing bolts.
(10) Choke plate mounting bolts.
(11) Choke plate rod and rod ends.
(12) Cross shaft and levers.
(13) Actuator shaft and indicator.
(14) Actuator rod and rod ends.
(15) Actuator lever angle.
(16) Cross shaft bearings.
Bore in bearings for cross shaft ... 15.880 ± 0.005 mm (.6250 ± .0002 in)
Diameter of surface on shaft for bearings ... 15.739 ± 0.050 mm (.6196 ± .0020 in)
Procedure To Assemble Actuator/Choke Linkage
a. Assemble choke plate and shaft (4), leaving bolts (10) loose.
b. Assemble thrust washer (5) and tighten four bolts (9) to ... 47 ± 9 N·m (35 ± 7 lb ft)
c. Fully close the choke plate and tighten bolts (10) to ... 12 ± 3 N·m (9 ± 2 lb ft)
e. Install the choke plate housing (3) and gaskets between aftercooler cover (1) and air inlet from turbocharger (2).
e. With choke plate and cover installed, hold choke plate in closed position and tighten adjusting bolt (8) until it makes contact with the stop plate.
f. Tighten the adjusting bolt an additional 90 ± 15 degrees and tighten the locking nut to ... 25 ± 6 N·m (18 ± 4 lb ft)
NOTE: Do not allow the set screw to turn while tightening the locking nut.
Procedure To Adjust Actuator/Choke Linkage
a. Assemble choke plate lever (6) on choke shaft and cross shaft lever (12) on choke end (stamped) of cross shaft.
b. While providing equal thread engagement, attach choke plate rod and rod ends (11) to choke shaft and cross shaft levers.
c. Adjust rod length until the choke is in the closed position and the choke plate lever (6) is 41.5 ± 1.5 degrees from the horizontal position and the cross shaft lever (7) angle is ... 28.0 ± 1.5 degrees
d. Tighten rod ends nuts to a torque of ... 25 ± 6 N·m (18 ± 4 lb ft)
e. With actuator shaft (13) in the closed (100 percent) position, install actuator lever. Actuator lever angle (15) should be ... 68.0 ± 2.5 degrees (from the horizontal position)
f. Install cross shaft lever (12) on actuator end of cross shaft (not stamped).
g. While providing equal thread engagement, attach rod and rod ends (14) to actuator lever and cross shaft lever.
h. With choke fully closed, adjust rod length until the actuator indicator (pointer) is between the 100 and 97 percent position.
NOTE: The 97 percent position is equal to 2.7 degrees CCW from the 100 percent position.
j. Tighten rod end nuts to a torque of ... 25 ± 6 N·m (18 ± 4 lb ft)
NOTE: The actuator indicator is calibrated to show the percentage not the engle that the choke plate is open or closed. An actuator indicator reading of 2.7 degrees is equal to approximately 2.5 percent.
Correct adjustment and lubrication of the mechanical actuator linkage should result in good engine operation over the entire speed/load range of the engine. If no load instability is encountered, and the mechanical linkage is adjusted correctly, the Digital Diagnostic Tool can be used to electronically "fine tune" the actuator to improve engine operation at no load conditions. Use the "CHOKE TRIM" mode and the instructions included with the DDT to make the adjustments.
Mechanical Choke Trim Procedure
The inlet manifold pressure can be adjusted by changing the length of the connecting rod linkage between the choke actuator and the choke plate. Refer to the Air Lines (Choke) section for choke linkage setting specifications.
1. Set engine operating condition to: rated speed, no load (or minimum load possible).
2. Loosen the jam nuts on the linkage rod that connects the choke actuator to the choke plate. This connecting rod has LH and RH threads on opposite ends.
3. To change the inlet manifold pressure adjust the length of the linkage rod.
NOTE: Increasing the length of the connection may disengage the connecting rod from the rod end assembly.
This process should be done slowly. Pause after every adjustment to allow the engine to respond to the change in the inlet manifold pressure.
Monitor the:
inlet manifold pressure
stability of the engine rpm
position of choke actuator
position of wastegate actuator
individual cylinder combustion burn times
individual cylinder exhaust port temperatures
4. After completion of the choke trim process, tighten the jam nuts on the linkage rod.
5. Confirm that all cylinders are firing by checking the combustion burn times for the cylinders (screen number 14 on the DDT). A combustion burn time greater than 12 ms indicates that the cylinder is misfiring. Also, check the cylinders for low exhaust port temperatures. If engine stability is unacceptable after properly completing the choke trim procedure, refer to the Governor Adjustment Procedure in Systems Operation, Testing and Adjusting, SENR5528.