Rayco C275, Operator, Service, Maintenance Manual, Page: 68 / 94

68
Track Drive Pumps
This machine is equipped with (2) Danfoss®-Danfoss series
42 pumps that propel the track drive motors. Each pump is
dedicated to a Left and a Right side track motor. The variable
displacement pump is a compact, high power density unit, us-
ing the parallel axial piston/slipper concept in conjunction with a
tilt-able swash plate to vary the pump’s displacement. Revers-
ing the angle of the swash plate reverses the flow of fluid from
the pump, and reversing the direction of rotation of the motor
output. Series 42 pumps provide an infinitely variable speed
range between zero and maximum in both forward and reverse.
6
11022637 • Rev. CD • June 2010
Series 42 Axial Piston Pumps
Technical Information
General description
Roller bearing
Swashplate
Piston
Valve plate
Charge pump
28/32/41/51 cm
3
cross-sectional view
Series 42 pumps are advanced hydrostatic units for medium power applications with
maximum loads of 415 bar [6017 psi] (28/41 cm 3 ) and 350 bar [5075 psi] (32/51 cm 3 ).
You can combine these pumps with a suitable Sauer-Danfoss motor or other products in
a system to transfer and control hydraulic power.
The Series 42 variable displacement pump is a compact, high power density unit, using
the parallel axial piston/slipper concept in conjunction with a tiltable swashplate to vary
the pump’s displacement.
Reversing the angle of the swashplate reverses the flow of fluid from the pump, and
reversing the direction of rotation of the motor output. Series 42 pumps provide an
infinitely variable speed range between zero and maximum in both forward and reverse.
Series 42 pumps use a cradle swashplate design with a hydraulic servo control cylinder.
Control is provided through a compact servo control system. A variety of servo controls
are available. These include mechanically- or electrically-actuated feedback controls,
hydraulic or electric proportional controls, and a three-position electric control. These
controls feature low hysteresis and responsive performance.
BasiC DesiGn
P100382E
To prevent premature wear, use only new clean fluid. Use a
filter capable of controlling
fluid cleanliness to ISO 4406 Class 22/18/13
All Series 42 pumps applied in closed circuit installations re-
quire charge flow to make up
for internal leakage, to maintain positive pressure in the main
circuit, to provide flow for
cooling, to replace any leakage losses from external valved or
auxiliary systems, and to
provide flow and pressure for the pump control system.
The charge relief valve maintains charge pressure at a desig-
nated level. Series 42 pumps
come with direct-acting poppet style charge relief valves. The
valve setting is set at the
factory. The setting is screw adjustable.
Caution: Incorrect charge pressure settings may result in
the inability to build required system pressure, inability
to control pump, and/or Inadequate loop flushing flows.
Maintain correct charge pressure under all operating con-
ditions.
Series 42 pumps are available with adjustable mechanical
displacement (stroke) limiters located in the servo covers. The
maximum displacement of the pump can be limited to any value
from its maximum displacement to zero in either direction. The
limiters are factory set slightly beyond the maximum displace-
ment of the pump. Displacement limiters may not be suited to
all applications.
22
11022637 • Rev. CD • June 2010
Series 42 Axial Piston Pumps
Technical Information
Features and options
DisPlaCement
limiteRs
Series 42 pumps are available with
adjustable mechanical displacement
(stroke) limiters located in the servo
covers. The maximum displacement of
the pump can be limited to any value
from its maximum displacement to
zero in either direction. The limiters
are factory set slightly beyond the
maximum displacement of the pump.
Displacement limiters may not be suited
to all applications.
Series 42 pump displacement limiters
looP flusHinG Series 42 pumps have an integral loop flushing valve for circuits requiring the removal of
excessive contamination or with high cooling requirements. We also provide an orificed
loop flushing relief valve. The orifice controls loop flushing flow in most conditions. A
Lo
0
1
2
3
4
5
6
7
8
9
10
0
0.5
1
1.5
2
2.5
0 5 10 15 20 25 30
0 100 200 300 400
Lo
op F
lushing
Flow (l/min)
Charge Pressure (bar)
[psi]
Opti
on 3
Optio
n 2
Optio
n 5
Optio
n 4
[US gal/min]
P100398E
Loop flushing valve
Loop flushing flow
combination of relief setting and orifice
size controls flushing flow. For proper
operation, ensure the loop flushing relief
valve is set at or below the charge relief
setting. Contact your Sauer-Danfoss
representative for application assistance.

CAUTION
Incorrect pressure settings may result
in the inability to build required system
pressure, insufficient control pressure,
and/or inadequate loop flushing flow.
Maintain correct charge pressure under
all operating conditions.
Series 42 pumps have an integral loop flushing valve for
circuits requiring the removal of excessive contamination or
with high cooling requirements. We also provide an orifice loop
flushing relief valve. The orifice controls loop flushing flow in
most conditions. A combination of relief setting and orifice size
controls flushing flow. For proper operation, ensure the loop
flushing relief valve is set at or below the charge relief setting.
CAUTION: Incorrect pressure settings may result in the
inability to build required system pressure, insufficient
control pressure, and/or inadequate loop flushing flow.
Maintain correct charge pressure under all operating con-
ditions.
22
11022637 • Rev. CD • June 2010
Series 42 Axial Piston Pumps
Technical Information
Features and options
DisPlaCement
limiteRs
Series 42 pumps are available with
adjustable mechanical displacement
(stroke) limiters located in the servo
covers. The maximum displacement of
the pump can be limited to any value
from its maximum displacement to
zero in either direction. The limiters
are factory set slightly beyond the
maximum displacement of the pump.
Displacement limiters may not be suited
to all applications.
Series 42 pump displacement limiters
looP flusHinG Series 42 pumps have an integral loop flushing valve for circuits requiring the removal of
excessive contamination or with high cooling requirements. We also provide an orificed
loop flushing relief valve. The orifice controls loop flushing flow in most conditions. A
Lo
0
1
2
3
4
5
6
7
8
9
10
0
0.5
1
1.5
2
2.5
0 5 10 15 20 25 30
0 100 200 300 400
Lo
op F
lushing
Flow (l/min)
Charge Pressure (bar)
[psi]
Opti
on 3
Optio
n 2
Optio
n 5
Optio
n 4
[US gal/min]
P100398E
Loop flushing valve
Loop flushing flow
combination of relief setting and orifice
size controls flushing flow. For proper
operation, ensure the loop flushing relief
valve is set at or below the charge relief
setting. Contact your Sauer-Danfoss
representative for application assistance.

CAUTION
Incorrect pressure settings may result
in the inability to build required system
pressure, insufficient control pressure,
and/or inadequate loop flushing flow.
Maintain correct charge pressure under
all operating conditions.