REED 00 C50SS, Руководство пользователя, Страница: 48 / 84

REED
00 MODEL:
C50SS
TRAILER CONCRETE PUMP
MAINT
PAGE 18
With this arrangement of connecting the two cylinders together, it is possible for various
reasons, such as leakage around the piston seals that more oil exists on the rod side of the
cylinder than is required. When this condition exists, some hydraulic oil remains at the rod
end of the cylinder being extended while the other cylinder is fully retracted. As a result the
cylinder cannot be totally extended and thus it
SHORT STROKES which will also happen
eventually to the other cylinder.
This condition can be corrected by actuating the switch on the electrical control box to
position
“A” or “B” whichever cylinder is extending, and to HOLD switch until extended
cylinder is fully bottomed out. Hydraulically, this is accomplished by use of the check valves
installed on both cylinders. By holding the
CYL A-B switch, you have interrupted the cycle
and are forcing more oil into the barrel of the extending cylinder. This oil is then directed and
unseats the check valve at the rod end of the extending cylinder
“A” , putting more oil on the
rod side which is then transferred to the rod side of CYL “B” . Since that cavity is full,
pressure is built up in the rod side of CYL “B” , which unseats the barrel side check valve
forcing the excess oil back to the tank. Once the extending cylinder is at full stroke, regular
operation can continue.
In addition to piston leakage, a SHORT STROKE
condition may result from incorrect proximity sensor
location or leaking check valves.
As protection to the
MAIN PUMP CIRCUIT against excessive pressure, a relief valve has
been installed and is set to open at 4200 PSI which is 200 PSI over the main system
pressure. Thus when the system pressure reaches 4200 PSI, the relief valve opens directing
the oil back to the tank.
S-TUBE SHIFT CIRCUIT (Refer to Hydraulic Schematic)
In the foregoing description of the Main Pump Circuit, we learned that the hydraulic drive
cylinders operate on an alternating basis causing the material cylinders to do the same.
Since there is only one outlet for the pumping material, a means is required to transfer the
material from the material cylinder to the outlet and into the delivery line. To accomplish this
a component referred to as the swing tube or S- tube is installed in the hopper. Since there
are two material cylinders and one S-tube, the S-tube must be shifted from one material
cylinder to the other, whichever one is loaded with the pumping material. Thus the
incorporation of a
S-TUBE SHIFT CIRCUIT .
REVISION: