The specified torque rating of the tapered shaft is based on the cross-sectional diameter of the shaft
through the keyway and assumes proper clamp and fit between shaft and coupling. Danfoss guarantees
the design and manufactured quality of the tapered shaft.
Danfoss has made provisions for the key in accordance to the ISO specification with the understanding
that the key is solely to assist in the installation of the mating coupling.
Charge Pump
Charge flow is required on all Series 90 pumps applied in closed circuit installations. The charge pump
provides flow to make up internal leakage, maintain a positive pressure in the main circuit, provide flow
for cooling and filtration, replace any leakage losses from external valving or auxiliary systems, and to
provide flow and pressure for the control system.
Many factors influence the charge flow requirements. These factors include system pressure, pump
speed, pump swashplate angle, type of fluid, temperature, size of heat exchanger, length and size of
hydraulic lines, control response characteristics, auxiliary flow requirements, hydrostatic motor type, etc.
Unusual application conditions may require a more detailed review of charge pump sizing. Charge
pressure must be maintained at a specified level under all operating conditions to prevent damage to the
transmission. Danfoss recommends testing under actual operating conditions to verify this.
Charge pump sizing/selection
In most applications a general guideline is that the charge pump displacement should be at least 10% of
the total displacement of all components in the system. Unusual application conditions may require a
more detailed review of charge flow requirements. Refer to
Selection of Drive line Components
BLN-9885,
for a detailed procedure.
System features and conditions which may invalidate the 10% guideline include (but are not limited to):
•
Continuous operation at low input speeds (< 1500 min
-1
(rpm))
•
High shock loading
•
Excessively long system lines (> 3m [9.8 ft])
•
Auxiliary flow requirements
•
Use of low speed high torque motors
•
High flushing flow
Contact your Danfoss representative for application assistance if your application includes any of these
conditions.
Available charge pump sizes and speed limits
Code
Charge pump size
cm³ [in³]
Rated speed
min-1 (rpm)
B
11 [0.69]
4200
C
14 [0.86]
4200
D
17 [1.03]
3900
E
20 [1.20]
3600
F
26 [1.60] (only for 130cc)
3300
H
34 [2.07]
3100
J
47 [2.82] (only for 180cc)
2600
K
65 [3.90]
2300
Charge pump flow and power curves
Charge pressure: 20 bar [350 psi]
Technical Information
Series 90 Axial Piston Pumps
Features and Options
46
520L0603 • Rev 0804 • March 2016
