Copyright © 1998 Rayco - All Rights Reserved
Printed in U.S.A.
RG 1672 DXH DIESEL SUPER CUTTER
TM
RAYCO
®
62
to the reservoir, where the oil is then recycled through
the hydraulic system. When the high pressure
overcomes opposing forces, the piston inside the
cylinder moves toward the exhausting body end port,
retracting the entire machine toward the trailer hitch,
and thus retracting the cutting wheel away from the
stump.
Likewise, in the SWING boom circuit, the high
pressure is directed to one or the other side of the
directional control valve, through the hand of the
operator. The circuit is similar to the cutting boom
motion circuits described above, except that two
opposing cylinders are used rather than just a single
cylinder. In the case of swinging cutting boom to the
left, for example, the operator pulls the SWING lever
toward him, and the valve spool shifts to allow high
pressure to the
rod
end port of the
left
cylinder and to
the
body
end port of the
right
cylinder, while
simultaneously the spool opens a passage that allows
fluid from the
rod
end port of the
right
cylinder and from
the
body
end port of the
left
cylinder, to exhaust
through the control valve body back to the reservoir,
where the oil is then recycled through the hydraulic
system.
Some additional elements enhance the boom
motion control circuit.
1. A SWING boom motion SPEED control (10) is
included in a line which connects the two
directional control valve ports leading to the
boom SWING cylinders. It is simply a hand-
operated needle valve. The farther it is opened,
the more leakage occurs between the two sides
of each cylinder, which slows down the cutting
boom swing motion. This can eliminate stalling
of the machine due to too much side pressure
against a stump, by requiring of the operator a
greater degree of lever movement for a given
change of boom motion speed.
2. Pilot check valves are located in the cutting
boom motion control circuit to reduce the risk of
uncontrolled falling or drifting of the boom.
Such might otherwise occur when the engine is
turned off or while on a slope:
A pilot check valve (12) is mounted in the
rod end port of the RAISE/LOWER
cylinder. It has a spring-loaded check
valve that prevents fluid from exhausting
from the cylinder rod end port to the
reservoir, so that the cutting boom cannot
fall without a signal from the control
valve. When the control valve sends high
pressure fluid to the body end port of the
cylinder, it also enters the pilot check
valve and overcomes the spring in the
check valve, opening flow again from the
cylinder rod end port to the reservoir.
Only then may the cutting boom lower,
under the control of the operator.
Likewise, a dual pilot check valve (13) is
located in both of the lines which direct
fluid to and from the SWING control valve
and the two boom SWING cylinders,
resisting uncontrolled boom movement
caused by momentum or gravity while on
the side of a hill or when transporting the
machine. It has spring-loaded check
valves that prevent fluid from flowing from
the low pressure cylinder ports to the
reservoir, so that the cutting boom cannot
swing left or right without a signal from
the control valve. Significant pressure
from the high pressure side of the
hydraulic system must enter the pilot
check valve, and hold open the low
pressure fluid flow valve, to enable low
pressure fluid to exhaust to the reservoir.
Only then will the cutting boom swing left
or right, under the control of the operator.
T
ROUBLE
-S
HOOTING
Summary of Contents for SUPER CUTTER RG 1672 DXH DIESEL
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