304C CR and 305C CR Mini Hydraulic Excavators Hydraulic System Caterpillar

Specifications

Usage:

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Illustration 1	g02214001
Relief valve locations (1) Main relief valve (2) Bucket cylinder rod end (3) Stick cylinder head end (4) Boom cylinder head end (5) Boom cylinder rod end (6) Bucket cylinder head end (7) Stick cylinder rod end (8) Swing left (9) Swing right (10) Pilot relief valve

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Table 1
304C CR
Relief Valve	Specifications
Main relief valve	24500 - 26000 kPa (3553 - 3771 psi)
Boom cylinder line (head end)	27250 ± 700 kPa (3952 ± 101 psi)
Boom cylinder line (rod end)
Stick cylinder line (head end)
Stick cylinder line (rod end)
Bucket cylinder line (head end)
Swing relief pressure (right)	21900 - 24900 kPa (3176 - 3611 psi)
Swing relief pressure (left)	21900 - 24900 kPa (3176 - 3611 psi)
Pilot relief valve	3400 ± 200 kPa (495 ± 30 psi)
Specifications (Main Pump)
Margin Pressure		1400 ± 200 kPa (203 ± 29 psi)
Minimum Flow		20 ± 3 L/min (5.3 ± 0.8 US gpm)
Maximum Flow		119 ± 3 L/min (31.4 ± 0.8 US gpm)

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Table 2
305C CR
Relief Valve	Specifications
Main relief valve	24500 - 26000 kPa (3553 - 3771 psi)
Boom cylinder line (head end)	27250 ± 700 kPa (3952 ± 101 psi)
Boom cylinder line (rod end)
Stick cylinder line (head end)
Stick cylinder line (rod end)
Bucket cylinder line (head end)
Swing relief pressure (right)	21200 - 24200 kPa (3075 - 3510 psi)
Swing relief pressure (left)	21200 - 24200 kPa (3075 - 3510 psi)
Pilot relief valve	3400 ± 200 kPa (495 ± 30 psi)
Specifications (Main Pump)
Margin Pressure		1400 ± 200 kPa (203 ± 29 psi)
Minimum Flow		31 ± 3 L/min (8.2 ± 0.8 US gpm)
Maximum Flow		130 ± 3 L/min (34.3 ± 0.8 US gpm)

Note: Normal operations of the engine and pumps are necessary for the pressure adjustments. 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".