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| Illustration 1 | g01420102 |
This Location is Under the Operator Compartment. (1) Solenoid "A" (2) High amplitude frequency adjustment (3) Low amplitude frequency adjustment (4) Solenoid "B" (5) Low amplitude relief valve | |
The vibratory pump is located under the operator compartment. The vibratory pump is splined to the drum pump. The vibratory pump provides flow to the closed circuit vibratory system.
The vibratory pump is similar to the propulsion pumps. Although, the direction control valve is operated by a solenoid. The swashplate control mechanism on the pump for the fixed frequency vibratory system does not have a feedback link.
The vibratory pump is controlled by two solenoids. On machines with the fixed frequency vibratory system, the pump control solenoids are on/off solenoids. On machines with the variable frequency vibratory system, the pump control solenoids are proportional solenoids. The control valves are the only difference between the hydraulic pumps that are used on the two different vibratory systems.
Solenoid "A" (1) is located on the top of the pump for both vibratory systems. On machines with the fixed frequency vibratory system, the amplitude control switch controls the power supply to the coil of solenoid "A". When the switch is in the HIGH AMPLITUDE position, solenoid "A" is energized. On machines with the variable frequency vibratory system, the vibratory controller uses solenoid "A" in order to control the vibration frequency when the amplitude control switch is in the LOW AMPLITUDE position.
The pump is equipped with displacement limiters. The adjustment screw (2) (high amplitude frequency) is located on the top face of the pump on both vibratory systems. This adjustment screw limits the maximum position of the swashplate when the amplitude control switch is in the HIGH AMPLITUDE position. The position of the swashplate controls pump output. Therefore, the swashplate position controls vibratory frequency.
Note: The position of this frequency adjustment screw is the same for all machines. While the function of the pump control solenoids is opposite between the two vibratory systems, the function of the frequency adjustment screws is the same between the two systems.
Solenoid "B" (4) is located on the bottom of the pump. On machines with the fixed frequency vibratory system, the amplitude control switch controls the power supply to the coil of the low amplitude solenoid. When the switch is in the LOW AMPLITUDE position, the low amplitude solenoid is energized. On machines with the variable frequency vibratory system, the vibratory controller uses solenoid "B" in order to control the vibration frequency when the amplitude control switch is in the HIGH AMPLITUDE position.
Frequency adjustment screw (3) (low amplitude) is located on the bottom face of the pump. This adjustment screw limits the maximum position of the swashplate when the amplitude selector switch is in the LOW AMPLITUDE position. The position of the swashplate controls pump output. Therefore, the position of the swashplate controls the vibratory frequency.
The pump housing contains two makeup and relief valves. There is one relief valve for low amplitude circuit (5). There is one relief valve for high amplitude circuit (not shown). The function of the relief valves limit maximum system pressure in the high amplitude and low amplitude circuits to 39000 ± 1500 kPa (5656 ± 218 psi).
The pump is also equipped with a charge relief valve (not shown). This valve is located on the bottom face of the pump.
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| Illustration 2 | g01420109 |
Vibratory Pump Off (1) Drive shaft (2) Servo piston (3) Directional control valve (4) Makeup and relief valve (5) Port plate (6) Swashplate (7) Slipper pad (8) Piston (9) Barrel assembly | |
Engine rotation turns the pump drive shaft. This action rotates the barrel assembly. The pistons in the vibratory pump rotate with the barrel assembly. The piston slipper pads allow the pistons to follow the angle of the swashplate. The pump only generates flow when the swashplate is not at the minimum angle.
When the vibratory system is not operating, both sides of the servo piston are open to the tank. The servo piston springs center the servo piston, and the swashplate remains at the minimum angle. With the swashplate at the minimum angle, the pistons do not move in and out of the barrel assembly as the pistons rotate. Therefore, the pump does not generate oil flow.
The pump is equipped with two makeup and relief valves. If the pressure in either closed circuit line falls below charge pressure, charge oil in the corresponding makeup valve unseats the makeup valve poppet. As the makeup valve poppet opens, charge oil enters the corresponding circuit. The charge circuit maintains pressure in the pump in order to keep the barrel assembly full of oil. Charge oil lubricates the pump components. Charge oil also cools the circuit and the charge oil replenishes the oil that is lost to internal leakage.
When pressure in the charge circuit is greater than 2600 ± 250 kPa (377 ± 36 psi), the oil pressure overcomes the spring force, and the charge relief valve opens. An orifice limits the amount of flow through the charge relief valve.
The pressure setting of the charge relief valve in the vibratory pump is less than the pressure setting of the charge relief valve in the drum pump. This fact ensures that oil is sent through the case drain of the vibratory pump under normal operating conditions. The charge relief valve in the vibratory pump will stop flow through the pump case if the charge pressure is less than 2600 ± 250 kPa (377 ± 36 psi). This function makes sure that flow through the orifice in the vibratory pump does not cause the charge pressure to decrease until the charge pressure is less than the brake release requirement if the system has excessive internal leakage.
The pump is controlled by two solenoids. One solenoid controls the high amplitude operation of the pump and the other solenoid controls the low amplitude operation of the pump. On machines that are equipped with the fixed frequency vibratory system, the solenoids are either fully on or the solenoids are fully off. The control solenoids do not provide variable control of the pump. On machines with the variable frequency vibratory system, the solenoids provide proportional control.
When a particular control solenoid is energized, charge oil is directed into the corresponding servo piston chamber, and the opposite servo piston chamber is open to the tank. The swashplate moves to the maximum angle. This will provide oil flow in order to operate the vibratory motor.
When the pump is operating, pressure in the high pressure circuit acts against the relief section in the makeup and relief valve in the high pressure circuit. If an external force causes the pressure in the high pressure circuit to increase above 39000 ± 1500 kPa (5656 ± 218 psi), the oil that is acting against the valve seat opens the relief valve. In this case, oil from the high pressure circuit flows into the charge circuit and into the low pressure circuit through the makeup valve in the low pressure circuit.