349D2 MHPU Mobile Hydraulic Power Unit Hydraulic System Specifications Caterpillar

Specifications

349D2 MHPU Mobile Hydraulic Power Unit Hydraulic System [M0064539]

349D2 MHPU Mobile Hydraulic Power Unit Hydraulic System Gear Pump (Pilot) - Test

HYDRAULIC SYSTEM

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340D2 L Mobile Hydraulic Power Unit Hydraulic System Hydraulic System Pressure - Release

349D2 MHPU Mobile Hydraulic Power Unit Hydraulic System Specifications

1.1. Specifications

Specifications

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Illustration 1	g06014524
Relief valve locations (A) Bucket cylinder line (head end) (B) Main relief valve (C) Stick cylinder line (rod end) (D) Boom cylinder line (rod end) (E) Bucket cylinder line (rod end) (F) Stick cylinder line (head end) (G) Boom cylinder line (head end) (H) Pilot relief valve (J) Pilot filter (K) Swing motor (left relief valve) (L) Swing motor (right relief valve) (M) Swing motor (N) Main control valve

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Table 1
Relief Valve	Specifications		Torque for Locknut
Relief Valve	New	Rebuilt	Torque for Locknut
(B) Main relief valve	35000 + 500 - 1000 kPa (5076 + 72 - 145 psi)		50 ± 10 N·m (37 ± 7 lb ft)
(G) Boom cylinder line (head end)	32800 kPa (4757 psi)⁽¹⁾		25 ± 2 N·m (18 ± 2 lb ft)
(C) Boom cylinder line (rod end)
(F) Stick cylinder line (head end)
(C) Stick cylinder line (rod end)
(A) Bucket cylinder line (head end)
(E) Bucket cylinder line (rod end)
(K) and (L) Swing relief pressure	31400 ± 1000 kPa (4550 ± 145 psi)		175 ± 10 N·m (130 ± 7 lb ft)
Left travel crossover relief valve (forward)	32800 kPa (4757 psi)⁽¹⁾
Left travel crossover relief valve (reverse)
Right travel crossover relief valve (forward)
Right travel crossover relief valve (reverse)
(H) Pilot relief valve	4100 ± 200 kPa (595 ± 30 psi)		16 ± 1 N·m (12 ± 1 lb ft)
Counterweight cylinder	20600 + 1000 kPa (2988 + 145 psi)

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⁽¹⁾

Minimum

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Table 2
Required Tools
Part Number	Description	Qty
9U-7400	Multitach Tool Group	1
8T-0470	Thermometer Group	1

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Table 3
Relief Valves	Pressure change With One Turn Of Adjustment Screw
Main valves	14400 kPa (2100 psi)
Line relief valve	11000 kPa (1600 psi)
Swing relief valve	6800 kPa (985 psi)
Travel crossover relief valve	13340 kPa (1925 psi)
Pilot relief valve	620 kPa (90 psi)

Note: Pressure values in Table 3 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 the engine and the pump characteristic curve needs to be checked. 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, "Hydraulic System Pressure - Release" and Testing and Adjusting, "Main Hydraulic Pump Air - Purge".