Motor-type flow-divider regeneration circuit – pressure-activated to full thrust

When it is necessary to get out of regeneration and into full thrust, add other valving to the motor-type flow-divider regeneration circuit.

Figure 11-37. Regeneration circuit with motor-type flow divider that can be pressure activated to full thrust. (Shown at rest with pump running.)

The regeneration circuit shown at rest in Figure 11-37 can be pressure activated to produce full thrust. Equal flow divider C is piped between the 4-way directional valve and the cylinder. The normal inlet port connects to the cylinder; one outlet connects to the directional valve; and the other outlet passes flow freely through pilot-operated check valve E to a tee in the cylinder cap-end line. Pilot-operated check valve E gets its pilot signal from the cylinder rod-end line before the flow divider port. Teed into the line between the flow divider and check E is the inlet to sequence valve D. Sequence valve D’s outlet tees into the cylinder rod-end line. Sequence valve D is internally drained and gets its external pilot signal from the cylinder cap-end line.

Figure 11-38. Regeneration circuit with motor-type flow divider that can be pressure activated to full thrust. (Shown with cylinder extending under regeneration.)

In Figure 11-38, solenoid A1 is energized so flow from the pump goes past the tee in the flow divider line to the cylinder cap-end. As the cylinder extends, oil from the rod end enters the flow divider. This oil splits; half goes to tank at no pressure, and half free-flows through pilot-operated check valve E to the cylinder cap-end tee at a pressure high enough to mix with pump flow. When the cylinder starts to extend, its speed quickly increases to almost twice speed. Maximum cylinder speed directly relates to the rod size. The larger the rod, the slower the speed. For a double rod-end cylinder, speed exactly doubles. As with any regeneration circuit, speed increases but force decreases.

Figure 11-39. Regeneration circuit with motor-type flow divider that can be pressure activated to full thrust. (Shown with cylinder extending at full power.)

When the cylinder meets resistance, pressure increases. When the cylinder butts against the work, as in Figure 11-39, pressure build up in the cap-end line pilots sequence valve D open. When sequence valve D opens, oil from both sides of the flow divider returns to tank at no pressure. At the same time, pilot-operated check valve E closes to keep the pump from relieving to tank. With the rod end of the cylinder hooked to tank and the pump feeding the cap end, the cylinder produces full thrust.

Figure 11-40. Regeneration circuit with motor-type flow divider that can be pressure activated to full thrust. (Shown with cylinder retracting.)

In Figure 11-40, the cylinder is retracting. By energizing solenoid B1, the 4-way directional valve sends pump flow to one outlet of the flow divider. Both of the motors in the flow divider turn at the rate of flow from the pump. During this part of the cycle, the motor — with its inlet teed into the cap-end line — acts as a pump. Pilot pressure from the cylinder rod-end port opens pilot-operated check valve E to allow this flow. Pump flow, plus the same flow from the second motor, makes the cylinder retract twice as fast as a conventional circuit. Again, however, cylinder thrust is only half that of a conventional circuit.

Motor-type flow divider regeneration circuit — solenoid-activated to full thrust

Other valving added to the motor-type flow-divider regeneration circuit produces an arrangement that can be switched to full thrust by activating a solenoid. Shown with the circuit at rest in Figure 11-41, equal-output flow divider C is piped between the 4-way directional valve and the cylinder. The flow divider’s normal inlet port connects to the cylinder; one outlet connects to the directional valve; and the other outlet passes flow freely through pilot-operated check valve E to a tee in the cylinder cap-end line. Check valve E receives its pilot signal from the cylinder rod-end line before the flow divider port. Teed into the line between the flow divider and the check valve is the inlet to normally closed directional-control valve D. Valve D’s outlet tees into the cylinder rod-end line. Valve D is direct solenoid operated and thus does not need a pilot supply.

Figure 11-41. Regeneration circuit with motor-type flow divider that can be solenoid activated to full thrust. (Shown at rest with pump running.)

When solenoid A1 of the main directional valve is energized — as in Figure 11-42 — flow from the pump goes past the flow divider line to the cylinder. As the cylinder extends, oil from its rod end enters the flow divider. The flow divider splits this oil; half of it goes to tank at no pressure, and the other half of it passes freely through pilot-operated check valve E to the cylinder cap end at a pressure high enough to mix it with pump flow. As the cylinder moves, its speed almost doubles. The amount of speed increase is directly related to the size of the piston rod. The larger the rod, the slower the speed. A double rod-end cylinder would go exactly twice as fast. As with any regeneration circuit, the speed increases but force decreases.

Figure 11-42. Regeneration circuit with motor-type flow divider that can be solenoid activated to full thrust. (Shown with cylinder extending under regeneration.)

When the cylinder rod trips a limit switch, as in Figure 11-43, the switch sends an electrical signal to solenoid-operated 2-way directional valve D, causing it to open. When valve D opens, oil from both sides of the flow divider returns to tank at no pressure. The cylinder slows before it contacts the work with this arrangement. At the same time, pilot-operated check valve E closes to prevent pump flow from bypassing to tank also. With the rod end of the cylinder connected to tank and the pump feeding the cap end, the cylinder generates full thrust.

Figure 11-43. Regeneration circuit with motor-type flow divider that can be solenoid activated to full thrust. (Shown with cylinder extending at full power.)

In Figure 11-44, the cylinder is retracting. Energized solenoid B1 shifts the 4-way directional valve to send pump flow to one outlet of the flow divider. Both of the motors in the flow divider turn at the rate of flow from the pump. During this part of the cycle, the motor — with its inlet teed into the cap-end line — acts as a pump. Pilot pressure from the cylinder rod-end port opens check valve E to pass this flow. Pump flow, plus the same flow from the second motor, makes the cylinder retract twice as fast as a conventional circuit. However, cylinder thrust is only half that of a conventional circuit.

Figure 11-44. Regeneration circuit with motor-type flow divider that can be solenoid activated to full thrust. (Shown with cylinder retracting.)