TM 9-2350-256-34-2
Table 2-3. Troubleshooting-Continued
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
MECHANICAL TRANSMISSION AND MAIN HYDRAULIC PUMP CIRCUIT
(MAIN HYDRAULIC SYSTEM) -Continued
Step 2. Inspect mechanical transmission for broken or restricted hose.
Replace mechanical transmission hose. Refer to TM 9-2350-256-20, Medium Recovery Vehicle, M88A1.
Step. 3. Inspect mechanical transmission output shaft to main hydraulic pump. If not rotating, proceed with mechani-
cal transmission clutch pressure check. Install pressure gage in mechanical transmission clutch pressure line.
For location, refer to TM 9-2350-256-20, Medium Recovery Vehicle, M88A1. With engine operating at 1800
rpm, and power control valve lever in ON position, normal operating pressure is 150 ±10 psi.
a. Remove mechanical transmission and main hydraulic pump assembly. Refer to TM 9-2350-256-34-1, Medium
Recovery Vehicle. M88A1.
b. Replace mechanical transmission. Refer to paragraph 3-16.
Step 4. Test for defective power control valve or restricted hose. Remove
hose no. 66 from mechanical transmission.
With mechanical transmission drive shaft rotating, and power control valve lever placed in ON position. oil
should flow from hose.
a. Replace defective power control valve. Refer to TM 9-2350-256-34-1, Medium Recovery Vehicle, M88A1.
b. Replace restricted or damaged hose. Refer to TM 9-2350-256-20, Medium Recovery Vehicle, M88A1.
16. MAIN HYDRAULIC PUMP FAILS TO ENGAGE
Step 1. Inspect for broken mechanical transmission and main hydraulic pump shaft coupling.
a. Remove mechanical transmission and main hydraulic pump assembly. Refer to TM 9-2350-256-34-1, Medium
Recovery Vehicle, M88A1.
b. Repair or replace shaft coupling. Refer to paragraph 3-16.
Step 2. Test for low hydraulic pressure to mechanical transmission clutch. Install pressure gage in mechanical trans-
mission clutch pressure hose. For location, refer to TM 9-2350-256-20, Medium Recovery Vehicle, M88A1.
With engine operating at 1800 rpm, and power control valve lever in ON position, normal operating pressure
should be 150 ± 10 psi.
a. Remove mechanical transmission and main hydrairlic pump assembly. Refer to TM 9-2350-256-34-1, Medium
Recovery Vehicle, M88A1.
b. Replace mechanical transmission. Refer to paragraph 3-16.
17. MECHANICAL TRANSMISSION OVERHEATING
Step 1. Inspect mechanical transmission for low oil level.
Add oil to bring to proper level. Refer to TM 9-2350-256-20, Medium Recovery Vehicle, M88A1.
Step 2. Test for faulty mechanical transmission lubrication pump. Remove pipe plug from mechanical transmission
test gage port and install pressure gage. For location of test gage port, refer to TM 9-230-256-20, Medium Re-
covery Vehicle, M88A1. With engine operating at 1800 rpm, normal operating pressure is 10 to 15 psi.
a. Remove mechanical transmission and main hydraulic pump assembly. Refer to TM 9-2350-256-34-1, Medium
Recovery Vehicle, M88A1.
b. Replace mechanical transmission. Refer to paragraph 3-16.
Step 3. Test for low hydraulic pressure to mechanical transmission clutch. Install pressure gage in mechanical trans-
mission clutch pressure hose. For location, refer to TM 9-2350-256-20, Medium Recovery Vehicle, M88A1. With
engine operating at 1800 rpm, and power control valve lever in ON position, normal operating pressure should
be 150 ± 10 psi.
a Remove mechanical transmission and main hydraulic pump assembly. Refer to TM 9-2350-256-34-1, Medium
Recovery Vehicle, M88A1.
b. Replace mechanical transmission. Refer to paragraph 3-16.
18. MECHANICAL TRANSMISSION SLIPPING OR CHATTERING
Step 1. Test for low hydraulic pressure to mechanical transmission clutch. Install pressure gage in mechanical trans-
mission clutch pressure hose. For location, refer to TM 9-2350-256-20, Medium Recovery Vehicle, M88A1. With
Change 7
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