Danfoss Charge pressure relief valve adjustment Installation guide

Service Kit Instructions

Series 90 variable pumps

Charge pressure relief valve adjustment

CHARGE PRESSURE		The following procedure explains how to check and adjust the charge pressure relief
RELIEF VALVE		valve.
ADJUSTMENT
		1. Install a 50 bar [1000 psi] pressure gauge in the pump charge pressure gauge port
	Warning	(M3). Install a 10 bar [100 psi] gauge to measure case pressure (tee into L1 or L2 or
	The following procedure	use servo gauge port M4 or M5). Operate the system with the pump in neutral (zero
may require the vehicle/		displacement) when measuring pump charge pressure.
machine to be disabled
(wheels raised o the		2. The table shows the acceptable pump charge pressure range for some charge relief
ground, work function		valve settings.These pressures assume 1500 min¯¹ (rpm) and a reservoir temperature
disconnected, etc.) in order		of 50°C [120°F], and are referenced to case pressure.
to prevent injury to the
technician and bystanders.
Take necessary safety		Charge pressure relief valve	Case drain port L1
precautions before moving
the vehicle/machine.			0 - 10 bar [0 - 100 psi]
		M4	1 1/16-12
		K90	115 N•m [85 lbf•ft]
		Adjusting screw

K10 Lock nut

52 N•m [39 lbf•ft]

Charge pressure gauge port M3 0 - 50 bar [0 - 1000 psi] 9/16-18

23 N•m [17 lbf•ft]

See appropriate table

M5

P106 162E

Listed pressures assume a pump speed of 1500 min-1 (rpm). At higher pump input speeds (with higher charge flows) the charge pressure will rise over the rated setting.

Charge pressure ranges

	Model code	Measured charge pressure*
	20	18.1 – 21.7 bar
		[262 –315 psi]

24

22.0 – 26.9 bar [319 – 390 psi]

28

25.8 – 30.7 bar [37.4 – 44.5 psi]

* This is the actual charge pressure port gauge reading minus the case pressure port gauge reading.

© Danfoss, 2013

11085721 • Rev AB • September 2013

1

CHARGE PRESSURE	3.		Later production Series 90 pumps have an external screw-adjustable charge
RELIEF VALVE			pressure relief valve. Loosen locknut (K10) and turn the adjusting screw (K90) using a
ADJUSTMENT			screwdriver or 1/2 in. hex wrench to adjust charge pressure setting.
(continued)
		Lock nut wrench size
		Frame size			Wrench size
		030 – 100			1-1/16 inch
		130 – 250			1-5/8 inch
	4.		Clockwise rotation of the plug increases the setting and counterclockwise rotation
			decreases the setting (at a rate of approximately 3.9 bar [50 psi] per turn).Torque
			lock nut to 52 N•m [39 lbf•ft].
	5.		Once you achieve the desired charge pressure setting, remove the gauges and plug
			the ports.

© Danfoss, 2013

11085721 • Rev AB • September 2013

2