320 GC, 320 and 323 Excavator Machine Systems Caterpillar

Specifications

Usage:

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Illustration 1	g06350489
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) Left travel crossover relief valve for forward travel (upper valve) (11) Left travel crossover relief valve for reverse travel (lower valve) (12) Right travel crossover relief valve for forward travel (upper valve) (13) Right travel crossover relief valve for reverse travel (lower valve) (14) Pilot relief valve (15) Main control valve (16) Travel motor (right) (17) Travel motor (left) (18) Swing motor

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Table 1
Relief Valve	Specifications		Torque for Locknut
Relief Valve	New Rebuilt⁽¹⁾	Service Limit⁽²⁾	Torque for Locknut
Main relief valve	35000 + 500 - 1000 kPa (5076 + 73 - 145 psi)	35000 + 500 - 2000 kPa (5076 + 73 - 290 psi)	50 ± 10 N·m (37 ± 7 lb ft)
Main relief valve (Heavy Lift)	38000 + 500 - 1000 kPa (5512 + 73 - 145 psi)	38000 + 500 - 2000 kPa (5512 + 73 - 290 psi)	69 ± 10 N·m (51 ± 7 lb ft)
Boom cylinder line (head end)	41000 ± 500 kPa (5947 ± 73 psi)	32800 kPa (4757 psi) ( 35800 kPa (5192 psi) Heavy Lift)	20 ± 2 N·m (14 ± 1 lb ft)
VA Boom cylinder line (head end)	41000 ± 500 kPa (5947 ± 73 psi)	32800 kPa (4757 psi) ( 35800 kPa (5192 psi) Heavy Lift)
Boom cylinder line (rod end)	38000 ± 500 kPa (5511 ± 73 psi)	32800 kPa (4757 psi)
VA Boom cylinder line (rod end)
Stick cylinder line (head end)
Stick cylinder line (rod end)	41000 ± 500 kPa (5947 ± 73 psi)	32800 kPa (4757 psi) ( 35800 kPa (5192 psi) Heavy Lift)
Bucket cylinder line (head end)	38000 ± 500 kPa (5511 ± 73 psi)	32800 kPa (4757 psi)
Bucket cylinder line (rod end)	38000 ± 500 kPa (5511 ± 73 psi)	32800 kPa (4757 psi)
Swing relief pressure (right)	25500 ± 1000 kPa (3698 ± 145)	25500 + 1000 - 2000 kPa (3698 + 145 - 290 psi)	117 ± 10 N·m (85 ± 7 lb ft)
Swing relief pressure (left)	25500 ± 1000 kPa (3698 ± 145)	25500 + 1000 - 2000 kPa (3698 + 145 - 290 psi)	117 ± 10 N·m (85 ± 7 lb ft)
Left travel crossover relief valve (forward)	37500 ± 1500 kPa (5439 ± 218 psi)	32800 kPa (4757 psi)	39.2 ± 4.9 N·m (28.9 ± 3.6 lb ft)
Left travel crossover relief valve (reverse)
Right travel crossover relief valve (forward)
Right travel crossover relief valve (reverse)
Pilot pressure reducing valve	4100 ± 300 kPa (595 ± 44 psi)		9.5 ± 1 N·m (84 ± 9 lb in)

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⁽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.

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Table 2
Relief Valves	Pressure Change With One Turn Of Adjustment Screw
Main valves	14400 kPa (2100 psi)
Line relief valve	24000 kPa (3480 psi)
Swing relief valve	6800 kPa (985 psi)
Travel crossover relief valve	8800 kPa (1276 psi)
Pilot pressure reducing valve	11000 kPa (1595 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".