Horizontal earth boring machine

Claim 2

A generally horizontal earth boring machine apparatus comprising: a generally horizontally disposed earth boring auger, a hydraulic motor operatively connected to said auger to rotate the latter in opposite directions, hydraulic actuator means operatively connected to said auger to move the latter axially in opposite directions, a variable displacement pump located in a selected position independently of the position of said motor and actuator means and having a discharge for delivering hydraulic fluid to said motor and actuator means, first directional control valve means controlling communication between said pump discharge and said motor, second directional control valve means controlling communication between said pump discharge and said actuator means, hydraulic means responsive to hydraulic pressure to vary the displacement of said pump, control means for delivering hydraulic fluid to said hydraulic means, said control means having a pair of signal ports, one of said signal ports being in communication with said pump discharge, first regulating means between said motor and the other of said signal ports and being responsive to pressure in said motor greater than in said actuator to communicate pressure to said other of said signal ports, second regulating means operatively disposed between said actuator means and said other of said signal ports and being responsive to pressure in said actuator means greater than in said motor to communicate pressure to said other of said signal ports, said hydraulic means being operative to vary the displacement of said pump to maintain a predetermined pressure differential between said pair of signal ports up to a predetermined pressure level at said pump discharge.

Claim 3

The combination of claim 1 and further comprising power limiting means communicating with said signal ports and being operative beyond said predetermined pressure level at said output port to deliver hydraulic fluid to said hydraulic means to decrease the displacement of said pump as pressure at said output port increases above said predetermined level.

Claim 4

The combination of claim 1 and further comprising power means for driving said variable displacement pump and in which said power means and said variable displacement pump are disposed in selected positions remotely from said earth boring auger.

Claim 5

The combination of claim 1 in which said control means includes power limiting means operative beyond said predetermined pressure level to maintain the product of hydraulic fluid flow and hydraulic pressure at a substantially constant value.

Claim 6

The combination of claim 1 in which said first and second directional control vAlve means each include an inlet for receiving fluid from said pump and an outlet for returning fluid to said pump, and further comprising pressure relief valve means between the inlet and the outlet of said first directional control valve means to determine the maximum pressure at said outlet port.

Claim 7

The combination of claim 5 further comprising pressure relief valve means between the inlet and the outlet of said second directional control valve means operable to open at a preaaure greater than said maximum pressure at said outlet port.

Claim 8

The combination of claim 1 in which said first and second directional control valve means are operable simultaneously and independently of each other.

Claim 9

A horizontal earth boring machine comprising: a carriage supported for horizontal movement, an elongated earth boring auger supported relative to said carriage for rotation relative thereto, a hydraulic motor operatively connected to said auger to rotate the latter in opposite directions, hydraulic actuator means operatively connected to said carriage to move the latter in opposite directions to advance and retract said auger, a pump having a discharge for delivering hydraulic fluid to said motor and said actuator means, first directional control valve means between said pump discharge and said motor for controlling the direction of rotation of said auger, second directional control valve means between said pump discharge and said actuator means for controlling the direction of movement of said carriage, adjusting means movable to vary the displacement of said pump, hydraulic servo piston means connected to said adjusting means and being responsive to hydraulic pressure to move the latter, control means for delivering hydraulic fluid to said servo piston means, said control means having a pair of signal ports, one of said signal ports being in communication with said pump discharge, first regulating means between said motor and the other of said signal ports and being responsive to pressure in said motor greater than said actuator to communicate pressure to said other of said signal ports, second regulating means operatively disposed between said actuator means and said other of said signal ports and being responsive to pressure in said actuator means greater than in said motor to communicate pressure to the other of said signal ports, said control means being operative to deliver hydraulic fluid to said servo piston means to vary the displacement of said pump to maintain a predetermined pressure differential between said pair of signal ports up to a predetermined pressure level at said pump discharge.

Claim 10

A horizontal earth boring machine comprising: a carriage supported for horizontal movement, an elongated earth boring auger supported relative to said carriage for rotation relative thereto, a hydraulic motor operatively connected to said auger to rotate the latter in opposite directions, hydraulic actuator means operatively connected to said carriage to move the latter in opposite directions to advance and retract said auger, a pump having a discharge for delivering hydraulic fluid to said motor and said actuator means, first directional control valve means between said pump discharge and said motor for controlling the direction of rotation of said auger, second directional control valve means between said pump discharge and said actuator means for controlling the direction of movement of said carriage, adjusting means movable to vary the displacement of said pump, hydraulic servo piston means connected to said adjusting means and being responsive to hydraulic pressure to move the latter, control means for delivering hydraulic fluid to said servo piston means, said control means having a pair of signal ports, one of said signal ports being in communication with said pump discharge, first regulating means between said motor and the other of said signal ports and being responsive to pressure in said motor greater than said actuator to communicate pressure to said other of said signal ports, second regulating means operatively disposed between said actuator means and said other of said signal ports and being responsive to pressure in said actuator means greater than in said motor to communicate pressure to the other of said signal ports, said control means being operative to deliver hydraulic fluid to said servo piston means to vary the displacement of said pump to maintain a predetermined pressure differential between said pair of signal ports up to a predetermined pressure level at said pump discharge.

Claim 11

The combination of claim 8 and further comprising power limiting means communicating with said signal ports and being operative beyond said predetermined pressure level at said pump discharge to deliver hydraulic fluid to said piston means to decrease the displacement of said pump as pressure at said output port increases beyond said predetermined level.

Claim 12

The combination of claim 9 in which an adjusting means is moved to decrease displacement of said pump as said pressure increases to maintain the product of displacement and pressure at a substantially constant value.

Claim 13

The combination of claim 9 in which said power limiting means is operatively connected to said adjusting means to decrease the displacement of said pump in response to an increase in pressure at said pump discharge and said other of said signal ports.

Claim 14

A generally horizontal earth boring machine comprising: a generally horizontal earth boring auger, a hydraulic motor operatively connected to said auger to rotate the latter in opposite directions, hydraulic actuator means operatively connected to said auger to move the latter axially in opposite directions, a variable displacement pump discharge for delivering hydraulic fluid to said motor and actuator means, first and second directional control valve means operatively disposed between said pump discharge and said motor and between said Pump discharge and actuator means, respectively, and each being movable from a neutral position to control the delivery of fluid to said motor and to said actuator means in proportion to the amount of movement of said valve means from said neutral position, hydraulic means responsive to hydraulic pressure to vary the displacement of said pump discharge, control means for delivering hydraulic fluid to said hydraulic means, said control means having a pair of signal ports, one of said signal ports being in communication with said pump discharge, means for deliver the highest of the fluid pressures downstream of said first and second control valve means to the other of said signal ports, said hydraulic means being operative to vary the displacement of said pump to maintain a predetermined pressure differential between said pair of signal ports up to a predetermined pressure level of said pump discharge, and power limiting means communicating with said signal ports and being operative beyond said predetermined pressure level at said pump discharge to deliver hydraulic fluid to said hydraulic means to decrease displacement of said pump as the pressure increases above said predetermined pressure level.

Claim 15

A generally horizontal earth boring machine comprising: a generally horizontal earth boring auger, a hydraulic motor operatively connected to said auger to rotate the latter in opposite directions, hydraulic actuator means operatively connected to said auger to move the latter axially in opposite directions, a variable displacement pump discharge for delivering hydraulic fluid to said motor and actuator means, first and second directional control valve means operatively disposed between said pump discharge and said motor and between said Pump discharge and actuator means, respectively, and each being movable from a neutral position to control the delivery of fluid to said motor and to said actuator means in proportion to the amount of movement of said valve means from said neutral position, hydraulic means responsive to hydraulic pressure to vary the displacement of said pump discharge, control means for delivering hydraulic fluid to said hydraulic means, said control means having a pair of signal ports, one of said signal ports being in communication with said pump discharge, means for deliver the highest of the fluid pressures downstream of said first and second control valve means to the other of said signal ports, said hydraulic means being operative to vary the displacement of said pump to maintain a predetermined pressure differential between said pair of signal ports up to a predetermined pressure level of said pump discharge, and power limiting means communicating with said signal ports and being operative beyond said predetermined pressure level at said pump discharge to deliver hydraulic fluid to said hydraulic means to decrease displacement of said pump as the pressure increases above said predetermined pressure level.

Claim 16

The combination of claim 12 in which said power limiting means is operative to maintain the flow of hydraulic fluid and the pressure thereof at said output port at a substantially constant value.

Claim 17

The combination of claim 12 in which said first and second control valve means are operative in said neutral positions of both of said control valve means to increase the pressure differential between said pair of signal ports to a predetermined amount above said predetermined pressure differential, and regulating means responsive to said last mentioned increase to actuate said hydraulic means to a position decreasing displacement of said pump to a minimum.

Claim 18

The combination of claim 12 in which said control valve means are operative in their neutral position to increase pressure at said one of said signal ports to increase pressure differential between said pair of signal ports to a value above said predetermined pressure differential, and regulating means operatively connected to said hydraulic means to actuate the latter to a position decreasing displacement of said pump to a minimum in response to an increase in pressure differential to said level above said predetermined pressure differential.