Cub Cadet 5000 Series - Manual (Page 8)

Domestic Series 5000 Hydraulics
4
1.26. When the tractor operator moves the control
lever forward to lower the three point hitch, the
lift control valve allows fluid to escape from the
lift cylinder as the cylinder retracts under the
weight of any accessories supported by the
hitch.
1.27. Increased fluid volume beyond normal return
flow rate is generated when the lift arms are low-
ered. This flow is exhausted through the top
inboard port (rearward facing elbow) back into
the transmission housing via a separate return
tube. See Figure 1.27.
2. HYDROSTATIC DRIVE: BASIC OPERATION
2.1. The input shaft to the BDU-21L-400 turns a shaft
that passes completely through the housing of
the hydro., driving an engine speed input shaft in
the transmission.
2.2. The input shaft drives the auxiliary hydraulic
pump and the P.T.O. They are driven at rela-
tively constant engine speed, rather than in rela-
tion to ground speed. See Figure 2.2.
2.3. The lower part of the pump contains a fixed dis-
placement axial piston hydraulic motor. The
motor is driven by the output of the variable dis-
placement pump.
2.4. The hydro. control arm (scissors bracket) moves
a swash plate that controls the output of the
pump.
Figure 1.27
Direct return
from lift valve
Figure 2.2
PTO clutch
PTO shaft
Pinion gears driving
auxiliary pump
Traction drive
pinion
Figure 2.4
Scissors bracket
Hydro
control
arm
Set screw