REED 00 C50SS, Manual, Page: 46 / 84

REED
00 MODEL:
C50SS
TRAILER CONCRETE PUMP
MAINT
PAGE 16
By making an internal change within the pump an external control, the flow output of the fluid
can be directed to either
“A” Port or “B” Port . As an example, from one side of the pump to
one drive cylinder with return fluid from the other cylinder going back to the pump, then
changing directions to pressure the other cylinder.
To meet the volume and pressure requirements of the main pump circuit, a Sundstrand
hydraulic pump is used. This pump is a variable displacement axial piston pump of a
swashplate design. The pistons run against the swashplate, which is capable of being tilted.
This tilting or angle varies the stroke length of the pistons which in turn varies the
displacement of the fluid. The larger the angle, the greater the flow. In the case of the Model
02 C50SS, the angle of the swashplate is varied by the use of the VOLUME control.
The main hydraulic pump is driven through a gear box by the diesel engine. Placing the
toggle switch to
ON will place the pump in operation. However, at this point since PUMP
switch if OFF , there is no volume demand, thus the charge pump within the main pump is
basically circulating the oil and lubricating the inside of the pump.
To energize the cycling circuit, the PUMP switch must be ON . When this is done, an
electrical signal is generated which engages the hydraulic pump to start and direct the flow to
the appropriate drive cylinder.
Where, how, and why is this electrical signal generated?
It was previously noted that the material pumping action is the result of the two material
cylinders cycling on an alternate basis. This alternating cycling is controlled by an electrical
signal that is generated at the end of each material cylinder’s suction, retraction stroke.
A proximity sensor, one for each material cylinder, is installed in the flush box. As the piston
coupler passes under the proximity sensor, it generates an electrical signal that is sent to the
logic controller or which is better known as the black box. The black box is a
REED
proprietary solid state device, designed to control the alternating action of the material
cylinders and to synchronize the movement of the swing tube. The signal from the black box
is then sent to the
PCP valve.
The PCP valve (pressure control pilot) is a component of the Sundstrand pump. When
energized it is used to convert the electrical signal to a hydraulic signal, which in turn, shifts
the hydraulic pumps servo piston. The servo piston is used to change the position of the
swashplate which is used to direct the flow of fluid to either
CYL “A” or “B” , based on the
signal received and which sensor was activated. The PCP valve is also used to vary the
angle of the swashplate which changes the displacement fo fluid to either a higher or lower
output in proportion to the amount of volume demand placed on it by the potentiometers
electrical signal.
REVISION: