Kubota M8540 Workshop Manual page 344

M8540, M9540, WSM
Partial Braking of Trailer Brake - Initiation
Piston (7) of control head (6) is pressurized through
control line X from the tractor service brake. Control
spool (2) is thus shifted to the left and separates from the
reservoir first brake line B and then bore (8). The control
spool (2) is shifted from position c to position e. The
control oil flow is blocked and hence flow control valve
(10) is switched into the regulating function in position b.
A constant flow Qk (approx. 30 L/min.) passes from port
P to the trailer brake through restrictor (11), bore (12),
check valve (13) and port B.
The restrictor (11) is designed for the constant flow
Qk. A residual flow Qp-Qk bypasses the flow control
valve (10), and then passes to the tractor hydraulic
through port N.
The pressure in the trailer brake line B is built up and
it acts on surface (1) of control spool (2) in opposition to
the pressure on piston (7).
(1) Piston Surface
(2) Control Spool
(3) Pressure Relief Element
(4) Spring
(5) Bleed Valve
(6) Control Head
(7) Piston
(8) Bore
(9) Throttle
(10) Flow Control Valve
(11) Restrictor
(12) Bore
(13) Check Valve
5-M7
BRAKES
P : Port for 3P Hydraulic Pump
N : Port for 3P Control Valve
B : Port for Trailer Brake
R : Port for Reservoir
(Transmission Case)
X : Port for Tractor Service
Brake
Qk : Brake Oil Flow
Qp : Delivery Flow
W1016704
KiSC issued 09, 2008 A