Hydraulic System

Location of Components
(1) Vibratory drum. (2) Eccentric weight shaft. (3) Vibratory control lever. (4) Tandem pump. (5) Single-pump drive. (6) Vibratory motor. (7) Cooling and test manifold.

Introduction

Vibratory Motor (6)

The vibratory system hydraulics let the operator control the vibratory action of the drum (1). The drum is made to vibrate by means of an eccentric weight shaft (2) inside the drum. The weight shaft is coupled to the vibratory motor (6), which rotates the weight shaft rapidly, causing the drum to vibrate.

Tandem Pump (4)

The vibratory motor (6) is a part of a closed-loop hydraulic system, powered by the rear section of the tandem pump (4). The tandem pump is mounted to a single-pump drive (5), which is driven by the machine engine. The tandem pump contains two separate pump units. The rear section of the pump (farthest from the single-pump drive) provides power to the vibratory system. The front section of the pump provides power to the propel system.

Reference: For information on the front section of the tandem pump, see Propel Systems Operation Testing and Adjusting, Form No. KEBR2373.

The rear section of the tandem pump (4) is a variable-displacement piston pump which provides minimum pressure to the system when the vibratory system is not operating. When not operating, the pressure of the oil in the system will be 1655 to 2140 kPa (250 to 310 psi).

Vibratory Control Lever (3)

The operator controls the vibratory system operation, using the vibratory control lever (3) on the operator's console. By moving this lever, the operator controls the flow of oil through the vibratory system.

Thus, the operator controls the direction of system oil flow, determining the rotational direction of the eccentric weight shaft. The construction of the weight shaft causes the drum to vibrate in high-amplitude when the shaft is rotated in one direction, and in low-amplitude when rotated in the opposite direction. The operator also controls the quantity of system oil flow, determining the vpm (vibrations per minute) of the drum. Normal operating range for the vibratory system is approximately 1400 to 1800 vpm.

Cooling and Test Manifold (7)

A portion of the hot oil in the closed-loop system is continually routed through the cooling and test manifold (7). The manifold ports this hot oil to the hydraulic oil tank. This permits fresh oil to enter the system regularly, keeping the components from over-heating. The cooling and test manifold has eight test ports which are used to check hydraulic pressure of the machine systems.

Single-Pump Drive

Single-Pump Drive
(1) Housing. (2) Drive shaft. (3) Drive plate.

The single-pump drive provides a direct mechanical connection between the tandem pump and the engine.

The components of the single-pump drive are drive plate (3), drive shaft (2), and housing (1).

Drive plate (3) is installed into the engine flywheel, and housing (1) is installed on the engine flywheel housing. Drive shaft (2) has external splines at one end, and internal splines at the other end. External splines of drive shaft mesh with splines of drive plate (3). Internal splines of drive shaft mesh with splines of tandem pump shaft.

When the engine is operating, the flywheel transfers torque through drive shaft to the tandem pump shaft. Pump shaft is always turned at engine rpm.

Pump Components

Rear Section of Tandem Pump in Off Position
(1) Displacement control valve. (2) Outlet for high-amplitude vibration. (3) Check/relief valve. (4) Charge oil passage. (5) Servo-piston. (6) Swashplate. (7) Rotating group. (8) Chamber. (9) Chamber. (10) Outlet for low-amplitude vibration. (11) Check/relief valve. (12) Case drain outlet.

The rear section of the tandem pump contains the following components:

* Displacement control valve (1). This valve is controlled by the operator with the vibratory control lever. As the displacement control valve is moved off center, it directs charge oil to the servo-piston, setting the displacement of the pump.

* Servo-piston (5). This is an opposed double-acting piston, which is spring-loaded to hold the swashplate in the center/stop position when the vibratory system is off. When the operator moves the vibratory control lever, the displacement control valve sends charge oil to one side or the other of the servo-piston, tilting the swashplate.

* Swashplate (6). The swashplate is mounted in cradle bearings, and is mechanically connected to the servo-piston. When the servo-piston moves, the swashplate tilts. This sets the displacement of the pump.

* Rotating Group (7). Consists of the pump input shaft, and an attached piston block with seven pistons. The input shaft is connected to the front section of the tandem pump, and rotates at engine rpm. When swashplate (6) is tilted, pistons stroke in and out of the piston block. This produces an output of high-pressure oil.

* Two check/relief valves (3) and (11). The check part of each valve directs charge oil to the rotating group to be used in the closedloop system. The relief part of each valve protects the system during operation. If system pressure exceeds 17 200 kPa (2500 psi), high-pressure oil flows through the relief valve to the low-pressure side of the pump.

Pump Operation

System Off

Rear Section of Tandem Pump in Off Position
(1) Displacement control valve. (2) Outlet for high-amplitiude vibration. (3) Check/relief valve. (4) Charge oil passage. (5) Servo-piston. (6) Swashplate. (7) Rotating group. (8) Chamber. (9) Chamber. (10) Outlet for low-amplitude vibration. (11) Check/relief valve. (12) Case drain outlet.

Filtered charge oil from the front section of the tandem pump enters the rear section of pump through charge oil passage (4). The charge relief valve (in front section of pump) maintains charge pressure at 1655 to 2140 kPa (250 to 310 psi).

Reference: For information on front section of tandem pump and charge filter, see Propel Systems Operation Testing and Adjusting, Form No. KEBR 2373.

Because the vibratory control lever (on operator's console) is off, the displacement control valve (1) is in the neutral position. This blocks charge oil flow to the servo-piston (5). The spring-loaded servo-piston holds the swashplate (6) in the center/stop position. Although the rotating group (7) is rotated by the single-pump drive, no high-pressure output oil is generated.

Charge oil opens the check part of the two check/relief valves (3) and (11), and applies pressure to the rotating group at chambers (8) and (9). Charge pressure also exits the pump through outlets (2) and (10), and is applied to both ports of the vibratory motor, and to two ports of the cooling and test manifold. Because charge pressure is equal at all ports, oil is blocked at the vibratory motor and at the cooling and test manifold. This results in "no flow" through the closed-loop system except for a small amount of case drain flow through the vibratory motor.

Case drain oil from the front section and the rear section of the tandem pump exits the pump through case drain outlet (12). This oil is routed through the propel motor to the hydraulic oil tank.

It is important to note that charge pressure is present at both rotating group chambers (8) and (9). This means that charge oil is available at any time to create high-pressure flow when the operator moves the vibratory control lever off center.

System On - High Amplitude

Rear Section of Tandem Pump in High-Amplitude Position
(1) Displacement control valve. (2) Outlet for high-amplitude vibration. (3) Check/relief valve. (4) Charge oil passage. (5) Servo-piston. (6) Swashplate. (7) Rotating group. (8) Chamber. (9) Chamber. (10) Outlet for low-amplitude vibration. (11) Check/relief valve. (12) Case drain outlet.

When the operator moves the vibratory control lever to the HIGH-AMPLITUDE position, the displacement control valve (1) shifts from the neutral position as shown. Filtered charge oil enters the pump through charge oil passage (4). Charge oil flows through the displacement control valve to servo-piston (5), causing swashplate (6) to tilt.

Swashplate angle is determined by how far the vibratory control lever is moved off center. Due to normal operating force changes, the swashplate tends to drift from the set position. Drift is sensed by the feedback linkage connecting the swashplate to the displacement control valve. This activates the displacement control valve, supplying pressure to the servo-piston and maintaining the swashplate in the set position.

As soon as the swashplate is tilted, the rotating group takes in charge oil at chamber (9), and creates high-pressure output oil at chamber (8). The passages connected to the intake side of the rotating group become the low-pressure side of the pump. The passages connected to the output side of the rotating group become the high-pressure side of the pump.

High-pressure output oil closes the check part of check/relief valve (3). The check part of check/relief valve (11) remains open so that incoming charge oil is added to the low-pressure side of the pump.

High-pressure oil exits the pump through outlet (2), and is routed to the vibratory motor. This causes the motor (and eccentric weight shaft) to rotate in the high-amplitude direction, creating vibratory action of the drum. Hydraulic oil leaving the vibratory motor is routed to the low-pressure side of the pump through outlet (10). Most of this oil is taken up by the rotating group at chamber (9), and is reused in the closed-loop system.

The high-pressure line and the low-pressure line to the vibratory motor are both connected to the cooling and test manifold. This allows some used oil to return to the hydraulic oil tank. Fresh charge oil flows through the check part of check/relief valve (11) to chamber (9). This replaces oil that leaves the system through the cooling and test manifold.

Charge relief valve (located in the rear section of pump) maintains oil in the low-pressure side of the pump at 1655 to 2140 kPa (250 to 310 psi).

Case drain oil from the front section and the front section of the tandem pump exits the pump through case drain outlet (12). This oil is routed through the propel motor to the hydraulic oil tank.

Check/Relief Valve (3) in Relief Position.
(13) Low-pressure side. (14) High-pressure side.

The relief part of check/relief valve (3) monitors the high-pressure side of the pump. If system pressure exceeds 17 200 kPa (2500 psi), the relief valve opens, passing oil to the low-pressure side of the pump.

System On - Low-Amplitude

Rear Section of Tandem Pump in Low-Amplitude Position
(1) Displacement control valve. (2) Outlet for high-amplitude vibration. (3) Check/relief valve. (4) Charge oil passage. (5) Servo-piston. (6) Swashplate. (7) Rotating group. (8) Chamber. (9) Chamber. (10) Outlet for low-amplitude vibration. (11) Check/relief valve. (12) Case drain outlet.

Tandem pump operation for low-amplitude vibration is similar to that for high-amplitude vibration. However, the high-pressure and low-pressure sides of the pump are switched around. Filtered charge oil enters the pump through charge oil passage (4) and encounters the displacement control valve (1).

When the operator moves the vibratory control lever to the LOW-AMPLITUDE position, the displacement control valve shifts as shown. Charge oil is routed through the displacement control valve to servo-piston (5). This tilts the swashplate (6) in the opposite direction from high-amplitude vibration.

The rotating group (7) takes in charge oil at chamber (8), and creates high-pressure output oil at chamber (9). High-pressure output oil closes the check part of check/relief valve (11). The check part of check/relief valve (3) remains open. This creates the high-pressure side and the low-pressure side of the pump.

High-pressure oil exits the pump through outlet (10), and is routed to the vibratory motor. This causes the motor (and eccentric weight shaft) to rotate in the low-amplitude direction, creating vibratory action of the drum. Hydraulic oil leaving the vibratory motor is routed to the low-pressure side of the pump through outlet (2). Most of this oil is taken up by the rotating group at chamber (8), and is reused in the closed-loop system.

Some used oil in the system is allowed to return to the hydraulic oil tank through the cooling and test manifold. As used oil leaves the system, fresh charge oil flows through check/relief valve (3) to chamber (8). This process continually replaces the oil in the closed-loop system.

Charge relief valve (located in the front section of pump) maintains oil in the low-pressure side of the pump at 1655 to 2140 kPa (250 to 310 psi).

Case drain oil from the front section and the rear section of the tandem pump exits the pump through case drain outlet (12). This oil is routed through the propel motor to the hydraulic oil tank.

Check/Relief Valve (11) in Relief Position.
(13) Low-pressure side. (14) High-pressure side.

The relief part of check/relief valve (11) monitors the high-pressure side of the pump. If system pressure exceeds 17 200 kPa (2500 psi), the relief valve opens, passing oil to the low-pressure side of the pump.

Motor

The vibratory motor is a fixed-displacement, bi-rotational, gear-type hydraulic motor. The motor output shaft is attached to one of the gears, and rotates as the gears are turned. The vibratory motor is mounted to the vibratory side of the drum. It drives the eccentric weight shaft, producing the desired vibratory action.

Vibratory Motor
(1) Case drain port. (2) High-amplitude pressure port. (3) Low-amplitude pressure port.

The two pressure ports (2) and (3) are connected to the high-pressure side and the low-pressure side of the tandem pump. When the vibratory system is off, charge oil enters the motor at both ports (2) and (3). The oil is blocked at the ports, and the gears do not turn.

When the system is operating in high-amplitude, high-pressure oil enters the motor at port (2). This causes the gears to turn, and the output shaft to rotate in the high-amplitude direction. Oil exits the motor at port (3) and is routed to the low-pressure side of the pump.

When the system is operating in low-amplitude, high-pressure oil enters the motor at port (3). This causes the gears to turn, and the output shaft to rotate in the low-amplitude direction. Oil exits the motor at port (2) and is routed to the low-pressure side of the pump.

Case drain oil always exits the motor through the case drain port (1), and flows back to the hydraulic oil tank.

Cooling and Test Manifold

Cooling and Test Manifold in Off Position
(1) Port T. (2) Passage from propel part of manifold. (3) Relief valve. (4) Shuttle valve spool. (5) Right side of shuttle valve spool. (6) Chamber. (7) Test port X2. (8) Port B. (9) Spring. (10) Left side of shuttle valve spool. (11) Chamber. (12) Test port X1. (13) Port A.

The cooling and test manifold is connected to the high-pressure side and the low-pressure side of the vibratory system, and the propel system. Its purpose is to remove hot, used hydraulic oil from the low-pressure side of the pump at a controlled rate. This allows fresh charge oil to enter the system regularly.

The vibratory part of the cooling and test manifold operates independently of the propel part (though they share a common return to the hydraulic oil tank).

Reference: Operation of the propel part of the cooling and test manifold is covered in Propel Systems Operation Testing and Adjusting, Form No. KEBR2373.

The vibratory part of the cooling and test manifold consists of a shuttle valve spool (4), a spring (9), and a relief valve (3). These parts are installed in an aluminum manifold. Port A (13) and port B (8) are connected to the high-pressure side and the low-pressure side of the tandem pump. Port X1 (12) and port X2 (7) are capped test ports used to measure the pressure at port A (13) and port B (8) respectively. Port T (1) is connected to a return line which leads through an oil cooler and hydraulic return filter, to the hydraulic oil tank.

Reference: For information on the oil cooler and hydraulic return filter, see Steer System Operation Testing and Adjusting, Form No. KEBR2249.

Cooling and Test Manifold Operation

System Off

Cooling and Test Manifold in Off Position
(1) Port T. (2) Passage from propel part of manifold. (3) Relief valve. (4) Shuttle valve spool. (5) Right side of shuttle valve spool. (6) Chamber. (7) Test port X2. (8) Port B. (9) Spring. (10) Left side of shuttle valve spool. (11) Chamber. (12) Test port X1. (13) Port A.

When the vibratory system is off, there is no high-pressure output oil from the vibratory pump. Thus, there is no high-pressure and low-pressure side of the pump - only charge pressure.

Charge pressure from one hydraulic line enters the manifold at port A (13). This oil is routed to the left side of shuttle valve spool (10), to chamber (11), and to test port X1 (12). Charge pressure from the other hydraulic line enters the manifold at port B (8). This oil is routed to the right side of shuttle valve spool (5), to chamber (6), and to test port X2 (7).

Because these two charge pressures are equal, spring (9) holds the shuttle valve spool (4) in the centered (closed) position. This blocks charge oil at chambers (11) and (6), preventing any oil flow through the manifold when the vibratory system is off.

System On - High-Amplitude

Cooling and Test Manifold in High-Amplitude Position
(1) Port T. (2) Passage from propel part of manifold. (3) Relief valve. (4) Shuttle valve spool. (5) Right side of shuttle valve spool. (6) Chamber. (7) Test port X2. (8) Port B. (9) Spring. (10) Leftside of shuttle valve spool. (11) Chamber. (12) Test port X1. (13) Port A.

High-pressure oil enters the manifold at port A (13). This oil is routed to the left side of the shuttle valve spool (10), to chamber (11), and to test port X1 (12). Low-pressure oil enters the manifold at port B (8). This oil is routed to the right side of the shuttle valve spool (5), to chamber (6), and to test port X2 (7).

High-pressure oil from port A overcomes force of spring (9) and low-pressure oil from port B. This causes shuttle valve spool (4) to shift to the right. High-pressure oil at chamber (11) is blocked. Low-pressure oil at chamber (6) flows through slots in shuttle valve spool (4) to the relief valve (3). The low-pressure oil opens the relief valve, allowing a controlled amount of oil to exit the cooling and test manifold through port T (1).

Oil leaving the manifold passes through an oil cooler and a hydraulic return filter (both are part of the machine steer system). This return oil is then routed to the hydraulic oil tank.

System On - Low-Amplitude

Cooling and Test Manifold in Low-Amplitude Position
(1) Port T. (2) Passage from propel part of manifold. (3) Relief valve. (4) Shuttle valve spool. (5) Right side of shuttle valve spool. (6) Chamber. (7) Test port X2. (8) Port B. (9) Spring. (10) Left side of shuttle valve spool. (11) Chamber. (12) Test port X1. (13) Port A.

Cooling and test manifold operation for low-amplitude vibration is similar to that for high-amplitude vibration. However, the high-pressure and low-pressure sides of the pump are switched around.

High-pressure oil enters the manifold at port B (8). This oil is routed to the right side of shuttle valve spool (5), to chamber (6), and to test port X2 (7). Low-pressure oil enters the manifold at port A (13). This oil is routed to the left side of shuttle valve spool (10), to chamber (11), and to test port X1 (12).

High-pressure oil from port B overcomes force of spring (9) and low-pressure oil from port A. This causes shuttle valve spool (4) to shift to the left. High-pressure oil at chamber (6) is blocked. Low-pressure oil at chamber (11) flows through slots in shuttle valve spool (4) to the relief valve (3).

The remainder of the cooling and test manifold operation for low-amplitude vibration is the same as for high-amplitude vibration.

Drum

Vibratory Drum
(1) Drum shell. (2) Weight bearing. (3) Eccentric weight shaft. (4) Weight bearing. (5) Magnetic sensor. (6) Sprocket. (7) Splined coupling (8) Drive shaft. (9) Drum support assembly. (10) Steel shot. (11) Weight. (12) Weight.

Vibratory action for the machine occurs at the smooth or padded drum assembly. Drive shaft (8) is splined at both ends. At the vibratory side of the drum, the drive shaft is connected to the vibratory motor with a splined coupling (7). At the brake side of the drum, the drive shaft meshes with the internal splines of the eccentric weight shaft (3). The eccentric weight shaft is held inside the drum by two weight bearings (2) and (4), one at each side of the drum.

When the operator turns the vibratory system on, the vibratory motor causes the drive shaft, the eccentric weight shaft (3), and the weights (11) and (12) to rotate. The eccentric weight shaft rides on weight bearings (2) and (4). Rotation of the two weights (11) and (12) creates vibratory action of the drum.

Eccentric Weight Shaft Rotation - High Amplitude
(3) Eccentric weight shaft. (10) Steel shot. (11) and (12) Weight.

The two weights (11) and (12) on the eccentric weight shaft (3) are loaded with steel shot (10). When the operator sets the vibratory system on high-amplitude, the eccentric weight shaft rotates in one direction. The steel shot is captured in one side of the weight compartment as shown above.

The weight of the shot in this position, increases the natural eccentricity of the weights. This causes the drum to vibrate in the high-amplitude state.

When the operator sets the vibratory system on low-amplitude, the eccentric weight shaft (3) rotates in the opposite direction. This causes the steel shot (10) to be captured in the opposite side of the weight compartment as shown below.

The weight of the shot in this position, offsets the natural eccentricity of the weights (11) and (12). This causes the drum to vibrate in the low-amplitude state.

Eccentric Weight Shaft Rotation - Low-Amplitude
(3) Eccentric weight shaft. (10) Steel shot. (11) and (12) Weight.

A sprocket (6) mounted on drive shaft (8), and a magnetic sensor (5) installed in the drum support assembly (9) measures drum vibrations in vpm (vibrations per minute). System vpm can be read on the vpm meter on the operator's console.