Multiquip manual LS400/LS500 Pump HOW IT Works, Pumping Cycle

LS400/LS500 PUMP — HOW IT WORKS

The following is a brief explanation of how the concrete cylinders, hydraulic cylinders, shuttle tube, valves and hopper work in sequence to pump concrete.

The hydraulic pressure is generated by a variable volume, pressure compensated, axial piston pump that is driven by a diesel engine. The rod sides of the drive cylinders are hydraulically connected together creating a “slave circuit,” which allows hydraulic oil to transfer from one piston to the other.

The two part cycling sequence is initiated by an electrical signal generated by two proximity switches activated by the drive cylinder.The proximity switches are normally open, magnetically sensing the movement of the main drive cylinder. As the drive cylinder piston head passes the proximity switch, an electrical signal is sent to the solenoid operated pilot valve which in turn directs pilot oil to the four valves controlling the drive cylinder and the shuttle cylinder.

A one-gallon accumulator assists the movement of the shuttle tube.This circuit assures that the shuttle tube will throw with the same intensity of each stroke regardless of how fast the main drive cylinders are cycling.

HIGH PRESSURE

TO TANK

OIL FROM PUMP

			PROXIMITY
HYDRAULIC			SWITCH
CYLINDERS
		SLAVE
		OIL
			CONCRETE
	A		CYLINDERS
			PISTON
		B	CUP

Figure 4. Pumping Cycle 2

In the first cycle, hydraulic pressure is applied to cylinder (B), causing the hydraulic piston, which is connected to the concrete piston and piston cup, to discharge concrete into the delivery line (Figure 3).

As one cylinder is discharging concrete, the hydraulic oil from the rod side (B) of the drive cylinders is being transferred through the slave circuit causing the opposite cylinder (A) to move back on the suction stroke, filling the cylinder with concrete.

SHUTTLE TUBE MOTION

SHUTTLE TUBE

The shuttle tube is sequenced to pivot to each concrete cylinder as the drive cylinders stroke to push concrete. As the second cycling sequence begins (Figure 4), the shuttle tube pivots to the opposite cylinder (A). The hydraulic piston passes under the proximity switch and sends pressure to the piston, causing it to stroke and discharge concrete into the delivery line. Hydraulic oil is transferred through the slave circuit to cylinder B, causing it to start a suction stroke, refilling it with concrete.The pumping sequence then repeats for the duration of the operation.

Figure 3. Pumping Cycle 1

MAYCO LS400/LS500 PUMP — OPERATION AND PARTS MANUAL — REV. #6 (09/19/11) — PAGE 17