Rayco C275, Operator, Service, Maintenance Manual, Page: 76 / 94

76
Track Drive Motors
This machine is equipped with (2) Danfoss®-Danfoss Series
51-1 motor cartridges that bolt into and drive the track drive
gearboxes. The Series 51 feature a bent-axis rotating group
that provides high starting torque and high speed. The ball
end of each piston runs in a bushing pressed into the drive
shaft. This permits the transfer of hydraulic power directly into
rotary motion at the drive shaft. The pressure balanced spheri-
cal piston rings maintain contact with the cylinder block bores
providing high volumetric efficiency and low friction. A constant
velocity joint (synchronizing shaft) keeps the rotation of the
cylinder block synchronized with the motor output shaft. A servo
piston changes the angle of the rotating group and varies the
displacement of the motor. Decreasing displacement increases
speed. Increasing displacement decreases speed. The Series
51-1 control feeds servo pressure directly to the servo piston.
Low system loop pressure for two-position controls.
In a closed circuit, hydraulic lines connect the main ports of the
pump to the main ports of the motor. Fluid flows in either direc -
tion from the pump to the motor and back to the pump. Either
of the hydraulic lines can be under high pressure. The direction
and speed of the fluid flow (and motor output shaft rotation) de -
pends on the position of the pump swash plate. The pump flow
and motor displacement determines motor output shaft speed.
The machine load determines the system pressure.
Series 51 motors are designed to accommodate a loop flush -
ing function. Installations that require additional fluid removal
from the main hydraulic circuit because of transmission cooling
requirements use a loop flushing function. The loop flushing
function consists of a shuttle valve and a poppet style relief
valve or an orificed relief valve cartridge.
The shuttle valve acts as a resolver, directing fluid only from
the low pressure side of the loop to the motor relief valve. The
shuttle valve is spring centered to the closed position to prevent
high pressure fluid loss from the circuit when reversing direc -
tions.
The poppet style relief valve regulates the charge pressure
level in the system circuit when there is a pressure differential
in the main loop.
When you use this valve, the pressure setting of the motor
must be less than the pump’s charge pressure setting. The
pressure setting of this valve is critical to achieving the proper
loop flushing flow rate.
11
11008567 • Rev AE • November 2009
Series 51 and 51-1 Motors
Service Manual
Introduction
In a closed circuit, hydraulic lines connect the main ports of the pump to the main ports
of the motor. Fluid flows in either direction from the pump to the motor and back to the
pump. Either of the hydraulic lines can be under high pressure.
The direction and speed of the fluid flow (and motor output shaft rotation) depends
on the position of the pump swash plate. The pump flow and motor displacement
determines motor output shaft speed. The machine load determines the system
pressure.
CloseD CiRCuit
PV
MV
Case
drain
line
Input
Output
Fl ow (Bi-directional)
Reser voir
P101 170E
A hydraulic line connects the outlet port of the pump to a directional valve in an open
circuit. The main ports of the motor connect to the working ports of this valve. When the
directional valve is actuated, fluid flows first from the pump to the valve. The directional
valve then directs the fluid to the motor in either direction.
The direction of fluid flow (and motor output shaft rotation) depends on the position
of the directional valve. The motor output speed depends on (1) pump output volume,
(2) the restriction of the valve opening and (3) motor displacement. The machine load
determines the system pressure. The directional valve routes fluid returning from the
motor to the reservoir. Additional components may be necessary to provide dynamic
breaking and to deal with overrunning loads.
oPen CiRCuit
PUMP MV
Fl ow
(Unidirectional)
Fl ow
(Bi-directional)
Input
Output
Case
drain
line
Reser voir
DIRECTIONAL
VA
LV
E
P101 171E
13
11008567
• Rev AE • November 2009
Series 51 and 51-1 Motors
Service Manual
Operation
Series 51 and 51-1 motors are designed to accommodate a loop flushing function.
Installations that require additional fluid removal from the main hydraulic circuit because
of transmission cooling requirements use a loop flushing function. The loop flushing
function consists of a shuttle valve and a poppet style relief valve or an orificed relief
valve cartridge.
The shuttle valve acts as a resolver, directing fluid only from the low pressure side of the
loop to the motor relief valve. The shuttle valve is spring centered to the closed position
to prevent high pressure fluid loss from the circuit when reversing directions.
looP flusHing
Loop flushing cross-section showing poppet style relief valve
Shuttle v alve
Poppet style
relief valv e
P101 267E
Loop flushing cross-section showing orificed relief valve
Orificed
relief v alve
Shuttle v alve
P101 266E
The poppet style relief valve regulates the charge pressure level in the system circuit
when there is a pressure differential in the main loop. When you use this valve, the
pressure setting of the motor must be less than the pump’s charge pressure setting. The
pressure setting of this valve is critical to achieving the proper loop flushing flow rate.
13
11008567 • Rev AE • November 2009
Series 51 and 51-1 Motors
Service Manual
Operation
Series 51 and 51-1 motors are designed to accommodate a loop flushing function.
Installations that require additional fluid removal from the main hydraulic circuit because
of transmission cooling requirements use a loop flushing function. The loop flushing
function consists of a shuttle valve and a poppet style relief valve or an orificed relief
valve cartridge.
The
shuttle valve
acts as a resolver, directing fluid only from the low pressure side of the
loop to the motor relief valve. The shuttle valve is spring centered to the closed position
to prevent high pressure fluid loss from the circuit when reversing directions.
looP flusHing
Loop flushing cross-section showing poppet style relief valve
Shuttle v alve
Poppet style
relief valv e
P101 267E
Loop flushing cross-section showing orificed relief valve
Orificed
relief v alve
Shuttle v alve
P101 266E
The
poppet style relief valve
regulates the charge pressure level in the system circuit
when there is a pressure differential in the main loop. When you use this valve, the
pressure setting of the motor must be less than the pump’s charge pressure setting. The
pressure setting of this valve is critical to achieving the proper loop flushing flow rate.
10 11008567
• Rev AE • November 2009
Series 51 and 51-1 Motors
Service Manual
Introduction
seRies 51-1 motoRs Series 51-1 motors feature simplified end cap and control components. The servo piston
in the Series 51-1 has a differential area of 2 to 1. The connecting joint is designed to
decrease the overall length of the motor.
The Series 51-1 control feeds servo pressure directly to the servo piston. Low system
loop pressure for two-position controls, and high system loop pressure for pressure
compensating controls actuates the servo piston.
Rotating hardware and housing components are common between Series 51 and Series
51-1.
Series 51-1 motor cross section
Serv o piston
Charge pressure relief v alve
Piston
Synchronizing shaf t
Tapered roller bearings
Speed pickup ring Bearing plate
Valv e segmen t
Minimum
displacement limiter
P101 174E
DIN-flange
Electrohydraulic two-position contro l
Speed sensor