Centaur 2001 950, Service Manual

Page: 432 / 450

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Axial Piston Pumps, Motors, and Transmissions Series 70 / 15 Series
General Technical Specifications (Continued)
1000 800 600 400 200 0
0
1
2
3
4
15 Series Implement Flow
(@ 3300 RPM and 180° F)
Pressure — psi
Implement Flow — gpm
15 PV
15 "U"
Displacement
15 PV — .33 cir
15 "U" — .30 cir
1000 800 600 400 200 0
0
1
2
3
BDU-21L Implement Flow
(@ 3200 RPM)
Implement Pressure — PSI
Implement Flow — gpm
(150° F)
(180° F)
Displacement
BDU-21L — .18 cir
Direct Displacement Control (DDC)
The Direct Displacement Control can be located on
either side of the Series 70 and 15 Series transmis-
sion or pump (except the BDP-10L). It provides a
simple, positive method of control. Movement of the
control shaft causes a proportional swashplate move-
ment, thus varying the pump’s displacement from full
displacement in one direction to full displacement in
the opposite direction.
Vehicle propel applications may require a provision
for non-linear control input to reduce control sensitiv-
ity near neutral. Damping or frictional forces may be
necessary to produce the desired control feel.
These units do not include any neutral centering
device for the swashplate. It is necessary to provide
a force in the machine’s control system that will hold
the swashplate at the desired angle. A “fail safe”
design which will return the swashplate to neutral in
the event of linkage failure is recommended.
WARNING
With no external forces applied to the swash-
plate trunnion, internal hydraulic forces may
not return the swashplate to the neutral posi-
tion under all conditions of operation.
The approximate torque necessary to rotate the
control per 1000 psi (70 bar) of system operating
pressure is as follows:
Series 70 BD-10 65 lbf•in per 1000 psi
(7.3 Nm per 70 bar)
Series 70 BD-21 100 lbf•in per 1000 psi
(11.3 Nm per 70 bar)
15 Series 65 lbf•in per 1000 psi
(7.3 Nm per 70 bar)
The maximum torque that should be applied to the
control under any condition is as follows:
Series 70 BD-10 200 lbf•in (22.6 Nm)
Series 70 BD-21 400 lbf•in (45.2 Nm)
15 Series 400 lbf•in (45.2 Nm)*
* With a maximum radial force of 100 lbsf (445 N)
applied to the control shaft not more than 3 inches
(76.2 mm) from the seal surface.
Implement Pump Performance
The following graphs provide typical implement pump
performance information for the Series 70-BDU-21L
and the 15 Series units.
BRAKING WARNING
The loss of hydrostatic drive line power in any
mode of operation may cause the loss of hy-
drostatic braking capacity. A braking system,
redundant to the hydrostatic transmission
must, therefore, be provided which is adequate
to stop and hold the system should the condi-
tion develop.