Vibrator Drive Hydraulic System

Introduction

Vibrator Motor Control Valve Manifold

Vibrator Motor (Gear Type)

Vibrator Motor (Piston Type)

The vibrator drive system consists of a vibrator pump, a Vibrator Motor Control Valve Manifold, and the vibrator motors.

The vibrator pump, mounted on the tractor, pumps hydraulic oil through the tractor portion of the vibrator drive system to a quick disconnect at the rear of the tractor.

Hydraulic oil flows from the quick disconnect to the vibrator motor control valve manifold (1). The control valve manifold (1) either blocks or allows the flow of hydraulic oil to the rest of the system. The amount of hydraulic oil allowed to flow to the system is also controlled by the valve manifold.

From the manifold, the hydraulic oil flows to the various vibrator motors (2).

Return oil from the vibrator motors flows back through the manifold (1) to another quick disconnect at the rear of the tractor.

From the quick disconnect, the oil flows through the tractor portion of the system.

See your tractor Service Manual for additional information on the tractor portion of the vibrator drive hydraulic system

Vibrator Motor Control Valve Manifold

Vibrator Motor Control Valve Manifold
(1) Manifold. (2) Flow control valve. (3) Relief valve. (4) 2-way solenoid valve. (5) Load control valve.

The vibrator motor control valve manifold consists of a manifold (1), a flow control valve (2), a relief valve (3), a 2-way solenoid valve (4), and a load control valve (5).

Manifold

The manifold provides the mounting ports for the valves, and the oil passages for hydraulic oil flow to the valves and through the manifold.

Flow Control Valve
(1) Inlet. (2) Outer spool. (3) Inner spool. (4) Adjusting screw. (5) Primary openings. (6) Secondary openings. (7) Inner spool opening. (8) Valve body.

Flow Control Valve

The flow control valve meters the amount of hydraulic oil which flows to the vibrator motors and returns excess hydraulic oil to the hydraulic oil tank.

Hydraulic oil entering the valve inlet (1), applies pressure to one end of the outer spool (2) before it passes through the opening (7) between the adjusting screw (4) and the inner spool (3).

After the hydraulic oil passes through the inner spool opening (7), it applies pressure to the other end of the outer spool (2) before it passes through the primary openings (5) in the valve body (8) and flows to the vibrator motors.

The difference between the pressures applied to the ends of the outer spool (2) constantly repositions the spool (2) inside the valve body (8). This ensures that the vibrator motors receive the proper flow of hydraulic oil through the primary openings (5) and that excess flow is returned to the hydraulic oil tank through the secondary openings (6).

Relief Valve
(1) Valve Inlet. (2) Spool. (3) Internal manifold. (4) Vent passage. (5) Ball and cap assembly. (6) Adjustment spring. (7) Spool opening.

Relief Valve

The relief valve is an internally piloted valve. The valve will relieve hydraulic oil pressure to the tank any time the pressure is 10 342 kPa (1500 psi) or higher. In addition, the relief valve has a vent port which ports hydraulic oil pressure to the 2-way solenoid valve.

Hydraulic oil flowing through the valve inlet (1), applies pressure to the spool (2) before flowing through an internal opening (7) in the spool. After the oil flows through the opening (7), it applies pressure to the other end of the spool (2) before flowing to the internal manifold (3) and through its oil passages.

One passage in the internal manifold directs the oil through a vent passage (4) and to the solenoid valve. Another passage directs the oil against the ball and cap assembly (5).

Relief Valve
(1) Valve Inlet. (2) Spool. (3) Internal manifold. (4) Vent passage. (5) Ball and cap assembly. (6) Adjustment spring. (7) Internal spool opening. (8) Relief oil passages. (9) Relief opening. (10) Return spring.

The adjustment spring (6) holds the ball and cap assembly (5) against the manifold (3) until the hydraulic oil pressure reaches the relief setting.

When the hydraulic oil pressure reaches the relief setting, the ball and cap assembly (5) is moved away from the internal manifold (3). Hydraulic oil then flows through relief oil passages (8) in the valve body to the hydraulic oil tank.

The hydraulic oil pressure on the manifold end of the spool (2) is thus lowered, allowing the pressure on the inlet end of the spool to move the spool (2) and uncover a relief opening (9) to the hydraulic oil tank. Hydraulic oil flows through this opening (9) until the hydraulic oil pressure is below the relief setting.

When the hydraulic oil pressure drops below the relief setting, the ball and cap assembly (5) is again pushed against the internal manifold (3). The pressures on each end of the spool (2) equalize; and the return spring (10) moves the spool (2) toward the valve inlet (1), covering the opening (9) to the tank.

Solenoid Valve and Relief Valve circuit
(1) Relief valve spool inlet. (2) Relief valve spool. (3) Return passage. (4) Solenoid valve spool. (5) Relief valve opening.

2-Way Solenoid Valve

The 2-way solenoid valve stops the vibrator motors by opening the relief valve in the manifold. The 2-way solenoid valve is controlled by the vibrator (Compactor) switch, mounted in the fuel burner control panel.

When the vibrator switch is moved to "Off", the solenoid valve spool (4) is positioned to allow the flow of hydraulic oil through the return passage (3). This lowers the hydraulic oil pressure on the manifold side of the relief valve spool (2). The pressure on the inlet end (1) of the spool moves the spool to uncover the relief valve opening (5) to the hydraulic oil tank. The output from the vibrator pump flows through the relief valve rather than to the vibrator motors.

When the switch is moved to "On", the valve spool (4) is positioned to block the flow of hydraulic oil through the return passage (3). The output from the vibrator pumps flows to the relief valve and, if the pressure is below the relief setting, to the flow control valve.

Load Control Valve
(1) Cavity. (2) Relief spool. (3) Main spring. (4) Relief opening.

Load Control Valve

The load control valve is a pilot operated valve. The valve opens and closes the manifold return passage from the motor in response to pilot pressure from the vibrator pump. This prevents the vibrator motors from attempting to continue turning once the machine has stopped.

Although the load control valve has a check valve, The check valve is not used in this application.

Pilot pressure enters a cavity (1) beneath the relief spool (2) and applies pressure against the spool (2). As long as the pilot pressure is less than the relief setting, the main spring (3) keeps the relief spool (2) covering the opening (4) from the motors.

When the pilot pressure exceeds the relief setting, the relief spool (2) is moved to uncover the opening (4). Return oil from the motors then flows through the valve and to the hydraulic oil tank.

Vibrator Motor (Gear Type)
(1) Cavity. (2) Inner Gear. (3) Outer gear. (4) Shaft. (5) Body.

Vibrator Motors (Gear Type)

These vibrator motors are fixed displacement, gear type motors which turn the vibrators.

Hydraulic oil enters the inlet port and flows into a cavity (1) formed by the inner gear (2) and outer gear (3). The pressure of the hydraulic oil forces the inner gear (2) and outer gear (3) and the attached shaft (4) to rotate within the body (5).

As the inner gear (2) and outer gear (3) rotate, the hydraulic oil passes through the outlet port and flows out of the pump.

Some gear motors used on the screeds also have a case drain port. This allows internal leakage from these motors to flow to the tractor hydraulic oil tank.

Vibrator Motor (Piston Type)
(1) Inlet port. (2) Inlet slot. (3) Backplate. (4) Piston block. (5) Pistons. (6) Drive shaft. (7) Outlet slot. (8) Outlet port.

Vibrator Motors (Piston Type)

These vibrator motors are fixed displacement, piston type motors which turn the vibrators.

Hydraulic oil enters the inlet port (1), flows through an inlet slot (2) in the backplate (3), and into cylinders in the piston block (4). The hydraulic oil forces against the pistons (5), causing the pistons (5) and piston block (4) to rotate. Since the piston block is splined to the drive shaft (6), the drive shaft (6) rotates along with the piston block (4).

As each piston block cylinder reaches the outlet slot (7) in the backplate, the hydraulic oil is forced out of the cylinder by the piston. The hydraulic oil then flows out the outlet port (8).

Internal hydraulic oil leakage between the motor components, flows out the case drain port and to the tractor hydraulic oil tank.

Proportional Flow Divider Valve (50/50 Valve)
(1) Inlet port. (2) Orifice. (3) Spool. (4) Passages. (5) Valve body. (6) Outlet ports. 50/50

Proportional Flow Divider Valve ( Valve)

On early V² screeds with only 3 motors, a proportional type, pressure compensated flow divider valve (50/50 valve) is included in the vibrator hydraulic circuit. The valve is located downstream from the main screed motor and serves to evenly split the flow of hydraulic oil flowing to the extension motors.

Hydraulic oil enters the inlet port (1) and flows through an orifice (2) in the spool (3). The oil flows out each end of the spool into a cavity at each end of the valve body. From the cavity the oil flows around the ends of the spool (3), through passages (4) in the valve body (5), and out the outlet ports (6). As the oil flows around the ends of the spool (3), hydraulic oil pressure is applied to each end of the spool (3).

If one of the motors begins receiving more hydraulic oil flow, the pressure at that end of the spool (3) will decrease. The higher pressure at the other end of the spool (3) will reposition the spool inside the valve body (5). The spool then partially blocks the passage to the motor receiving more flow, decreasing the amount of hydraulic oil that can flow through the passage.

As the hydraulic oil flow decreases, the pressure on the spool increases. The spool is moved toward its original position and the hydraulic oil flow is once again evenly split between the motors.

Screed Extension System

Introduction

Solenoid Valve

VIP Screed Extension Cylinder

V² Screed Extension Cylinder

The screed extension system consists of the auxiliary pump, two solenoid valves, and two screed extension cylinders.

The auxiliary pump, mounted on the tractor, pumps hydraulic oil through the auxiliary system to a quick disconnect at the rear of the tractor.

Hydraulic oil flows through the quick disconnect to the solenoid valves (1). Each solenoid valve (1) is controlled by an extension switch, one switch in each screed control junction box. In addition, each solenoid valve controls one of the two extension cylinders (2).

The extension cylinders (2) are used to extend and retract the screed extensions.

Manually Operated Valve (Early Screeds)

Early VIP Screeds

Some early VIP screeds have a manually operated valve (4) in place of the extension switch and solenoid valve. The valve is a self-centering 4-way spool valve with a pilot operated check valve.

On these screeds, hydraulic oil from the auxiliary pump flows to the valve. The valve either blocks or allows hydraulic oil flow to the extension cylinder controlled by the valve.

When the valve handle is in the center position, the valve spool is centered and hydraulic oil flow through the valve is blocked.

When the valve handle is moved toward the end of the screed, the valve spool is positioned to port hydraulic oil flow to the rod end of the extension cylinder, extending the cylinder.

When the valve handle is moved toward the center of the screed, the valve spool is positioned to port hydraulic oil flow to the head end of the extension cylinder, retracting the cylinder.

Solenoid Valves
(1) Windings. (2) Plunger. (3) Valve Body. (4) Pressure port. (5) Spool. (6) Return port.

Solenoid Valves

The solenoids (windings and plungers) are controlled by the extension switches. Depending on the position of the extension switches, the solenoid valves: block the flow of hydraulic oil, port hydraulic oil to the rod end of an extension cylinder, or port oil to the head end of an extension cylinder.

When the one of the switches is moved to the left or the right, one of the windings (1) is energized and the plunger (2) is moved by electromagnetic force.

Hydraulic oil enters the valve body (3) through a pressure port (4) and flows through the passages opened by the position of the spool (5).

Hydraulic oil leaving the valve body (3) through these passages will flow in one of three directions: through the valve return port (6) to the hydraulic oil tank, to the head end of an extension cylinder, or to the rod end of an extension cylinder.

Extension Cylinder
(1) Head end port. (2) Rod end port. (3) Rod. (4) Head.

Extension Cylinders

The extension cylinders are double acting cylinders; high pressure oil enters the head end port (1) of the cylinder to extend it and high pressure oil enters the rod end port (2) to retract it. The rod (3) extends out of the rod end of the cylinder, the opposite end is the head or cap end (4) of the cylinder.

When an extension cylinder is extended or retracted, the extension controlled by the cylinder is extended or retracted.

The return oil from the extension cylinders flows back through the solenoid valves and to another quick disconnect at the rear of the tractor. From the quick disconnect, the hydraulic oil flows through the tractor auxiliary return system.

See your tractor Service Manual for additional information on the auxiliary hydraulic system.

Pavemaster Screed Optional Strike-off Extension System

Introduction

Solenoid Valve

Extension Cylinder

The optional strike-off extension system consists of the auxiliary pump, two solenoid valves (1), and two strike-off extension cylinders (2).

The operation of the system is identical to the operation of the screed extension system for the VIP and V² screeds. See "Screed Extension System" on page 20 for further details.

Fuel Burner System

Introduction

Fuel Manifold

Burner Assembly (VIP Screeds)

Burner Assembly (V² and Pavemaster Screeds)

The fuel burner assembly provides a means of heating the screed before and during operation.

The system consists of an electrical fuel pump, mounted on the tractor, a fuel manifold (1), and the burner assemblies (2).

The fuel pump is controlled by a switch mounted in the burner control panel. When the switch is at "On", the fuel pump delivers diesel fuel from the tractor fuel tank to a quick disconnect at the rear of the tractor. From the quick disconnect the fuel flows through inline filters to the fuel manifold.

The fuel flows through the manifold and into outlet passages in the manifold. A supply ball valve (3) is mounted in each outlet passage.

Depending upon the position (open or closed) of each supply valve (3), the fuel is blocked or allowed to flow to each burner assembly.

The burner assemblies provide the means for burning the fuel and conveying heat to the bottom plate on the screed.

Fuel Manifold

Fuel Manifold
(1) Inlet passage. (2) Outlet passages. (3) Supply valves.

The fuel manifold provides the ports and passages for supplying the fuel to the burner assemblies. The manifold has an inlet passage (1) and four outlet passages (2).

A supply valve (3) is mounted in the outlet end of each outlet passage, and serves to block or allow the flow of fuel to each burner assembly.

Burner Assemblies (VIP Screeds)
(1) Fan. (2) Fan housing. (3) Baffles. (4) Blower mount. (5) Glow plug. (6) Elbow. (7) Inline filter. (8) Nozzle.

Burner Assembly (VIP Screeds)

The burner assemblies consists of a fan (1), a fan housing (2), two baffles (3), a blower mount (4), a glow plug (5), an elbow (6), an inline filter (7), and a nozzle (8).

Fuel flows from the fuel manifold to the elbow (6). From the elbow (6) the fuel flows through the inline filter (7) before it is sprayed from the nozzle (8). The glow plug (5) provides the heat source for initial ignition of the diesel fuel.

The fan (1) and fan housing (2) serve to circulate the air heated by the burning fuel to the screed bottom plate. (See Electrical System for additional information.)

Burner Assembly (V² and Pavemaster Screeds)
(1) Fan. (2) Fan housing. (3) Upper burner housing. (4) Lower burner housing. (5) Glow plug. (6) Elbow. (7) Nozzle. (8) Combustion head. ²

Burner Assembly (V and Pavemaster Screeds)

The burner assemblies consist of a fan (1), a fan housing (2), an upper burner housing (3), a lower burner housing (4), a glow plug (5), an elbow (6), a nozzle (7), and a combustion head (8).

Fuel flows from the fuel manifold to the elbow (6) and is sprayed from the nozzle (7).

The glow plug (5) provides the heat source for initial ignition of the diesel fuel.

The fan (1) and fan housing (2) serve to circulate air past the combustion head (8) where it can be heated by the burning fuel. The combustion head vanes divert the air flow into a circular pattern. The heated air then flows to the screed bottom plate. (See Electrical System for additional information.)

Screed Electrical System

Introduction

The screed electrical system consists of three separate electrical systems: the vibrator electrical system, the burner electrical system, and the screed control system. All three systems receive electrical power from the tractor electrical system.

Vibrator Switch

Solenoid Valve

Vibrator Electrical System

The vibrator electrical system turns the vibrators on or off. The system consists of the vibrator ("Compactor") switch and a solenoid valve.

The vibrator switch is mounted in the burner control panel ("Main Junction Box") and the solenoid valve is mounted in the vibrator motor control valve manifold. For additional information on the vibrator motor control valve manifold, see the hydraulic section of this module.

The vibrator switch is a two-position toggle switch. Depending upon the position of the vibrator switch ("On" or "Off"), the switch completes or breaks the circuit between the tractor electrical supply and the solenoid valve.

Solenoid Valve
(1) Solenoid. (2) Poppet. (3) Seat. (4) Springs.

The solenoid valve is a normally closed, poppet type valve. When the electrical circuit is completed by the vibrator switch, the solenoid (1) is energized. The solenoid moves the poppet (2) off its seat (3), allowing hydraulic flow through the valve. When the circuit is broken by the vibrator switch, the solenoid (1) is de-energized. Springs (4) inside the valve reposition the poppet (2) onto its seat (3), blocking hydraulic flow through the valve.

For additional information on the solenoid valve, see the Screed Hydraulic System portion of this module.

Burner Control Panel
(1) Fuel pump switch. (2) Glow plug switches.

VIP Screed Burner Assembly
(3) Glow plug. (4) Fan assembly.

V² and Pavemaster Screed Burner Assembly
(3) Glow plug. (4) Fan assembly.

Burner Electrical System

The burner electrical system controls the glow plugs and fans mounted in the burner assemblies. The systems consists of the fuel pump switch (1), a glow plug switch (2) for each burner assembly, and a glow plug (3) and a fan assembly (4) mounted in each burner assembly.

The fuel pump switch is a two-position toggle switch that controls the electrical fuel pump mounted on the tractor. When the switch is at the "On" position, the fuel pump is energized and transfers diesel fuel from the tractor fuel tank to the screed fuel burner system. When the switch is at the "Off" position, the fuel pump is de-energized and the transfer of fuel is stopped.

The glow plug switches are three-position toggle switches. Each switch controls one fuel burner assembly. Depending upon the position of the switch ("Off", "Glow Plug", or "Fan"), the switch breaks or completes the circuits to a burner assembly glow plug and fan.

When the switch is at the "Off" position, the electrical circuit to that glow plug and fan are broken.

When the switch is at the "Glow Plug" position, the circuit to that fan is broken, the circuit to the glow plug is completed, and electrical current flows through the glow plug. The resistance of the glow plug coils causes the coils to heat up, providing a heat source for the ignition of diesel fuel sprayed through the assembly.

When the switch is at the "Fan" position, the circuit to that glow plug is broken and the circuit to the fan is completed. The fan rotates, forcing air through the burner assembly. The air is heated by the burning diesel fuel before flowing into the screed baffle.

Screed Control System

Solenoid Valves

Screed Control Junction Box

The screed control system provides control of the extension cylinders for both the screed extensions on the VIP and V² screeds and the extendable strike-offs on the Pavemaster screeds. The system also provides control of the tractor conveyors, and the tow point cylinders. The system consists of two solenoid valves and two screed control junction boxes, one box at each end of the screed. Each junction box contains 1 two-position toggle switch, 4 three-position toggle switches, a relay and a potentiometer.

Extension Control

Extension Switch

A three-position toggle switch ("Extension" switch) in each junction box and one of the solenoid valves control the extension cylinder at the same end of the screed as the switch. The switch breaks or completes the circuits to the valve solenoids.

When the switch is in the center position, the circuits to both solenoids are broken and no hydraulic oil flows through the valve.

When the switch is moved to the outboard position, one of the solenoids is energized. The valve spool is moved to port hydraulic oil through the valve to the head end of the cylinder, extending the cylinder. As the cylinder extends, it moves the screed extension outboard, extending the screed extension out from the main screed.

When the switch is moved to the inboard position, the other solenoid is energized. The valve spool is moved to port hydraulic oil to the rod end of the cylinder, retracting the cylinder. As the cylinder retracts, it moves the screed extension inboard, retracting the screed extension into the main screed.

Conveyor Control

Conveyor Control
(1) Feeder sensitivity switch. (2) Feeder switch.

Two three-position switches, the "Feeder Sensitivity" switch (1) and the "Feeder" switch (2), in each junction box control the sensitivity of the feeder control sensors and provide control of the tractor conveyors.

Feeder Sensitivity Circuit

Feeder Control Sensor

Feeder Sensitivity Switch

The feeder control sensors, mounted on the tractor, control the swashplate angle of the conveyor pumps and the feeder sensitivity switches control the sensitivity of the feeder control sensors. Each sensor sensitivity switch sets the sensitivity of the feeder control sensor at the same end of the screed.

To determine the sensitivity, the position of the switch configures a number of resistors into a network. This network of resistors determines how far the sensor arm must move before the sensor begins changing the conveyor pump swashplate.

When the switches are at the "H" position, the swashplate angle is not changed until the sensor paddle moves outward to the 30 degree position. When the switches are at the "M" position, the swashplate angle is not changed until the paddle moves 15 degrees outward. In the "L" position, the sensor begins changing the swashplate angle as soon as the arm and paddle move from the vertical position.

For additional information on the feeder sensors, see the Service manual for your tractor.

Feeder Switch

Feeder Switch

Each feeder switch provides control of the conveyors on that side of the machine.

When the switch is in the lower ("Off") position, the switch breaks the circuit between the feeder sensor and the conveyor pump, stopping the conveyors.

When the switch is in the center position, the conveyors are controlled automatically by the feeder control sensor.

When the switch is in the upper ("Override") position, the feeder sensor is bypassed and the conveyor pump swashplate is moved to run the conveyors at full speed.

The tractor consoles may also contain feeder switches with similar functions to the feeder switches mounted on the screed. If your tractor is equipped in this manner, a tractor or a screed switch can change the function selected by the other except when either switch is at the "Override" position.

Tow Point Control

Tow Point Control Switches
(1) Potentiometer (inside panel). (2) Auto Manual switch. (3) Up Down switch.

The potentiometer (1), the two-position "Auto Manual" switch (2), and the three-position "Up Down" switch (3), in each junction box control the tow point cylinders.

Auto Manual Switch

Auto Manual Switch

The Auto Manual switch determines whether or not the tow point system is controlled automatically or manually.

When the switch is at the "Auto" position, the tow point cylinder is controlled automatically by the slope controller or the grade controller at the same side of the machine.

When the switch is at the "Manual" position, the cylinder is controlled by the Up Down switch mounted in the junction box.

Up Down Switch

Up Down Switch

The Up Down switch provides manual control of the position of the tow arm cylinder at the same side of the machine. The switch is connected to the servo valve for the cylinder.

When the switch is at the center position, the circuit between the switch and the servo valve is broken. The servo valve spool is centered and hydraulic oil flow to the cylinder is blocked.

When the switch is at the upper ("Up") position, an electrical signal is sent to one of the servo valve terminals. This causes the servo valve spool to be moved to port oil to the head end of the cylinder, extending the cylinder.

When the switch is at the lower ("Down") position, an electrical signal is sent to the other servo valve terminal. This causes the servo valve to port oil to the rod end of the cylinder, retracting the cylinder.

For additional information on the tow point cylinders and servo valves, see the Service manual for your tractor.

Potentiometer

The potentiometer controls the reaction speed of the tow point cylinder by controlling the amount of electrical current sent to the tow point servo valve. The greater the current sent to the servo valve, the more the servo valve spool will be moved and, thus, the greater the flow of hydraulic oil that is sent to the tow point cylinder.

For additional information on the tow point servo valves, see the Service manual for your tractor.