SYSTEMS OPERATION
TM 5-3805-263-14&P-3
around the valve spool, through outlet (5) and through
the line and lock check valve into the rod end of the lift
cylinder. The orifice in the passage from valve spool (2)
Lock check valves with outlet chokes are in the circuits
to outlet (5) is larger than the orifice for outlet (4). The oil
for the cylinders for articulation, the cylinder for
flow from the pump through outlet (5) to the rod end of
centershift and for the lift cylinder on The right side. The
the lift cylinder is approximately 6 U.S. gpm (22.7 litre/
lift cylinder on the left side, and on some machines, the
min).
ripper cylinder and the scarifier cylinder, have lock check
valves with relief valves. The relief valve is in the
The oil in the passage to outlet (5) goes through resolver
passage in the valve to the line for the rod end of a
valve (7) into passage (8) to the chamber for spring (14).
cylinder. When the implement valve is in HOLD position,
The pressure of the oil in the spring chamber controls
the oil in lines (8) and (10) is stopped and the rod in the
the output and the pressure of the pump the same way
cylinder cannot move. The springs against balls (6) and
as given in the explanation for the implement valve in
(7), and the oil ill lines (8) and (10), keep the balls on
LOWER position.
seats (9). The oil in lines (1) and(3) is at tank pressure.
The control lever (1) and valve spool (2) are the other
Moving the control lever for the blade lift on the right side
controls for the rate of oil flow from the pump to the
to the LOWER position lets the pump oil from the
implement. The shorter distance the valve spool is
implement valve, go through line (3). The pump oil holds
moved from the HOLD position, the smaller the amount
choke (5) away from the orifice in the passage and the
of oil (gpm or litre/min) that goes through the outlets of
oil goes into the chamber in the seat. The pump oil in
the implement valve to the implement.
the seat moves piston (2) against ball (6). Then the
pressure of the pump oil in the seat moves the piston,
ball (6) and ball 17) off seats (9). The pump oil through
Lock Check Valve
line (3) now goes through the lock check valve, through
There is a lock check valve, between the implement
line (10), and into the head end of the lift cylinder.
valve and the hydraulic cylinders, in each of the
The oil in the cylinder moves the piston and rod
implement circuits. The operation of each lock check
(connected to the blade) down. When the piston moves
valve is the same, but there are three types of lock check
down, it pushes the oil from the rod end of the cylinder
valves. One of the types of lock check valves is in the
through line (8), past ball (6) and moves choke (4) over
circuit for the cylinder for the leaning wheel, and on some
the orifice in the passage to line (I). The restriction to oil
machines, the cylinder for the blade tip, the cylinder for
flow through choke (4) prevents gravity from moving the
the side shift and the cylinder for the ripper
blade down faster than the pump oil can push the blade
down.
LOCK CHECK VALVE
(With outlet chokes)
1. Line to implement valve. 2. Piston. 3. Line to
implement valve. 4. Choke in outlet. 5. Choke in outlet.
6. Ball. 7. Ball. 8. Line to rod end of cylinder. 9.
Seats. 10. Line to head end of cylinder.
3-18
