Da - Automatic Speed-Related Control - Bosch Rexroth A6VM series 71 Manual

22 A6VM series 71 | Axial piston variable motor
DA – Automatic speed-related control
DA – Automatic speed-related control
The variable motor A6VM with automatic speed-related
control, type DA, is intended for use in hydrostatic travel
drives in combination with the variable pump A4VG with
DA control.
A drive-speed-related pilot pressure signal is generated by
the A4VG variable pump, and that signal, together with the
operating pressure, regulates the swivel angle of the
hydraulic motor.
Increasing pump speed, i.e. increasing pilot pressure,
causes the motor to swivel to a smaller displacement
(lower torque, higher speed), depending on the operating
pressure.
If the operating pressure exceeds the pressure setpoint set
on the controller, the variable motor swivels to a larger
displacement (higher torque, lower speed).
▶ Pressure ratio p /p
St HD
DA closed loop control is only suitable for certain types of
drive systems and requires review of the engine and vehicle
parameters to ensure that the motor is used correctly and
that machine operation is safe and efficient. We recommend
that all DA applications be reviewed by a Bosch Rexroth
application engineer.
Detailed information is available from our sales organiza-
tion.
Note
The beginning of control and the DA characteristic curve
are influenced by case pressure. An increase in case pres-
sure causes a decrease in the beginning of control (see
page 6) and thus a parallel shift of the characteristic.
Response time damping
The response time damping is influencing the stroke char-
acteristics of the motor and thus the reaction speed of the
machine.
Standard with Size 60 to 215
DA with one sided throttle pin effects the stroking time of
the motor from V to V
g min
▼ Overview Throttle Pins
Size 60
Groove [inch] 0.018
size
[mm] 0.45
Bosch Rexroth Corp., RE-A 91610/12.2015
= 5/100
. (as to table)
g max
85 115 150 170
0.018 0.022 0.022 0.022
0.45 0.55 0.55 0.55
DA0 hydraulic travel direction valve, negative control
Depending on the direction of rotation (travel direction),
the travel direction valve is switched by using pilot pres-
sures connections X
Direction
of rotation
cw
ccw
▼ Circuit diagram DA0
U T
1
T
2
215
0.022
0.65
or X .
1 2
Operating
pressure in
A
B
X
3
G
V
g min
V
g max
M
1
Pilot pressure in
X
1
X
2
X
1
X
2
B
A