352F Mobile Hydraulic Power Unit (MHPU) Machine Systems Specifications Caterpillar


Specifications
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Illustration 1g06060069
Relief valve locations
(1) Main relief valve
(2) Boom cylinder line (head end)
(3) Boom cylinder line (rod end)
(4) Stick cylinder line (head end)
(5) Stick cylinder line (rod end)
(6) Bucket cylinder line (head end)
(7) Bucket cylinder line (rod end)
(8) Swing (right)
(9) Swing (left)
(10) Pilot relief valve
(11) Main control valve
(12) Pilot filter
(13) Right swing motor
(14) Left swing motor

Table 1
Relief Valve  Specifications  Torque for Locknut 
New
Rebuilt(1)
Service Limit(2) 
Main relief valve  35000 ± 500 kPa (5076 ± 73 psi)  33000 kPa (4786 psi) to 35500 kPa (5150 psi)  50 ± 10 N·m (37 ± 7 lb ft) 
38000 ± 500 kPa (5512 ± 73 psi)
(Heavy Lift)
36000 kPa (5221 psi) to 38500 kPa (5584 psi)  75 ± 10 N·m (55 ± 7 lb ft) 
Boom cylinder line (head end)  40000 ± 500 kPa (5802 ± 73 psi)  > 32800 kPa (4757 psi)  24 ± 3 N·m (18 ± 2 lb ft) 
Boom cylinder line (rod end)  37000 ± 500 kPa (5366 ± 73 psi)  > 32800 kPa (4757 psi) 
Stick cylinder line (head end) 
Stick cylinder line (rod end)  40000 ± 500 kPa (5802 ± 73 psi)  > 32800 kPa (4757 psi) 
Bucket cylinder line (head end)  37000 ± 500 kPa (5366 ± 73 psi)  > 32800 kPa (4757 psi) 
Bucket cylinder line (rod end) 
Swing relief pressure (right) 334-9975 Swing Motor Gp  31400 ± 1000 kPa (4554 ± 145 psi)  29500 kPa (4279 psi) to 32000 kPa (4641 psi)  118 ± 10 N·m (87 ± 7 lb ft) 
Swing relief pressure (left) 334-9975 Swing Motor Gp 
Swing relief pressure (right) 486-5236 Swing Motor Gp  29000 ± 1000 kPa (4206 ± 145 psi)  27000 kPa (3916 psi) to 30000 kPa (4351 psi) 
Swing relief pressure (left) 486-5236 Swing Motor Gp 
Pilot relief valve  4100 ± 200 kPa (595 ± 29 psi)  49 ± 5 N·m (36 ± 4 lb ft) 
Counterweight relief valve  20600 + 1000 - 0 kPa (2988 + 145 - 0 psi)  55 ± 10 N·m (40 ± 7 lb ft) 
(1) A New specification is the performance that can be expected for a new machine. A “Rebuild” specification is the performance that can be expected after rebuilding the components of a system.
(2) Performance beyond “Service Limit” specifications is an indication of the following problems: improper adjustment, wear, damage of relief valves and damage of pumps.

Table 2
Relief Valves  Pressure change With One Turn Of Adjustment Screw 
Main valves  14400 kPa (2100 psi) 
Line relief valve  9300 kPa (1350 psi) 
Swing relief valve (right)  6800 kPa (985 psi) 
Swing relief valve (left)  10000 kPa (1450 psi) 

Note: Pressure values in Table 2 are approximate values. Use a pressure gauge for adjustment.

Note: Normal operations of the engine and pumps are necessary for the pressure adjustments. If the results of the pressure adjustment are not correct, then check the engine and the pump characteristic curve. Slow output flow from the pump is an indication of air in the hydraulic system. Make sure that no air is present in the hydraulic system. Refer to Testing and Adjusting, "Main Hydraulic Pump Air - Purge".

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