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Major hydraulic components ....................................5
hydraulic oil tank
hydrostatic pump
gear pump
primary valve bank Major hydraulic components
(Reference Fig. 30)
The hydraulic oil tank located on the left hand side of the machine has a 175 gallon capacity and is equipped with a oil level sight glass, high temperature switch and low oil level switch.
The hydrostatic pump located within the power unit is an axial piston, variable displacement and hydraulic displacement control pump that supplies hydraulic power to the conveyor.
The gear pump located within the power unit supplies hydraulic power to the primary and secondary valve banks. The pump stroke and direction of flow is controlled by the proportional detented valve.
The primary valve bank, located on the right hand side of the machine, is used to control the machine’s tilt, lift, tram, and power fill functions and to control flow to the secondary valve bank. All sections of the valve bank are spring return (self centering) except for the power fill section which is detented.
The secondary valve bank, located at the head shaft on the right hand side of the machine, is used to control tailpiece steering and tilt, the roof cylinders, and the foot cylinders.
The tank fill pump is located on the right hand side of the discharge section of the machine, to the left of the starter box, and is used to replenish oil to the hydraulic tank from an external source. The pump is capable of delivering approximately 5 gallons of fluid per 30 seconds.
The tank fill hand pump is located directly behind the tank fill pump on the right side of the discharge section of the machine, to the left of the starter box, and is used to manually replenish oil to the hydraulic tank from an external source.
The tilt hydraulic cylinders are located at the end of the crawler under the hopper on each side of the machine and are used to adjust the discharge height of the machine. Both cylinders are controlled by one section of the valve bank.
The lift hydraulic cylinders are located at the pivot point of the crawler on each side of the machine and are used to adjust the ground clearance of the machine. Each cylinder is individually controlled by separate sections of the valve bank.
secondary valve bank
tank fill pump
tank fill hand pump
tilt hydraulic cylinders
lift hydraulic cylinders
WARNING! The tilt and lift hydraulic cylinders have counterbalance cartridges which serve as load holding valves. Do not replace these cylinders with different style cylinders or the machine may fall. The machine could be damaged or you or other personnel could be seriously injured or killed by the falling machine. The machine is equipped with lock pins that should be installed when the unit is not being moved. Pin are located near the lift cylinders on both sides of the machine.
________________________________________________________________ 5.32 Bucyrus –Model 7MFBHM-48DD Feeder Breaker
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tram motors
conveyor motor
loop flushing valve
oil/water heat exchanger
proportional conveyor speed/direction control valve
charge filter
pressure filter (s)
return filter
tank fill filter
pressure filter (hydrostatic)
conveyor pressure gauge (6,000 psi)
auxiliary function pressure gauges
The tram motors are located to the inside of each crawler assembly and are used to supply power to the torque hubs for tramming operations. Each tram motor is individually controlled by separate sections of the valve bank.
The conveyor motor is located on the right hand side of the head shaft and is a radial piston motor that receives hydraulic fluid from the hydrostatic pump.
The machine is equipped with a loop flushing valve located on the discharge end of the machine on the frame side plate behind the hydrostatic pump. The valve is used to strip off approximately 3 gpm of the charge oil to flush the case of the conveyor motor.
The heat exchanger located on the right side of the machine is used to remove heat from the hydraulic circuit prior to dumping into tank.
The conveyor control valve located above the right hand crawler at the primary operator’s station is used to control the conveyor speed and direction of travel.
The charge filter is located on the right hand side of the machine on the filter tree located between the starter and the heat exchanger and is used to filter the charge fluid. The filter removes hot oil from the circuit, allowing the charge pump to replenish the circuit with cooler oil.
There are two (2) non-bypassing filters hard plumbed to two (2) bypassing filters located above the crawler on the right hand side of the machine at the primary operator’s station and are used to filter fluid on the pressure side of the primary valve bank circuit.
The return filter located on the right hand side of the of the discharge end of the machine on the bottom of the filter tree, between the starter and the heat exchanger, is used to filter return flow from the primary valve bank and the diversion valve.
The tank fill filter located beside the starter enclosure is used to filter fluid that is being pumped with the power fill system or the hand pump from an external source to the hydraulic oil tank.
The pressure filter is located on the right hand side of the discharge end of the machine on the top of the filter tree, between the starter and the heat exchanger, and is used to filter oil in the hydrostatic (conveyor) loop while the conveyor is running forward. The filter bypasses when the conveyor is running in reverse.
The conveyor pressure gauge is a 6,00 psi gauge located on the right side of the machine gives the operator a constant reading of the hydraulic pressure within the conveyor circuit.
The auxiliary function pressure gauges are high pressure gauges (6,000 psi) located below the tram control levers. These gauges give the operator a constant reading of the secondary system pressures.
charge pressure gauge (600 psi)
filter service indicator gauges (6,000 psi)
upper belt spreader cylinder
lower belt spreader cylinder
The charge pressure gauge is a low pressure gauge (600 psi) located on the right side of the machine. This gauge gives the operator a constant reading of the charge pressure.
The filter service indicator gauges are a set of 6,000 psi gauges located at the primary operator’s station on the right side of the machine. The gauges are used to determine the amount of contamination in the nonbypass filters (conveyor and two auxiliary) by allowing the pressure drop across the filters to be measured. The filter service indicator gauges are located downstream of the filter while the corresponding pressure gauges are located upstream of the filter. If the differential pressure reading (filter service indicator gauge - pressure gauge) exceeds 150 psi, the filter needs changed.
Table 1: Corresponding pressure gauges
Pressure gauge
Corresponding filter service indicator gauge
“CONVEYOR PRESSURE #4” “FILTER SVC INDICATOR #1” “AUXILIARY PRESSURE #2” “FILTER SVC INDICATOR #2” “AUXILIARY PRESSURE #3” “FILTER SVC INDICATOR #3”
There is one upper belt spreader cylinder located on each side of the tailpiece. The cylinders are used to raise and lower the upper belt spreader.
There is one lower belt spreader cylinder located on each side of the tailpiece. The cylinders are used to raise and lower the lower belt spreader.
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Fig. 31: Hydraulic schematic
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