Internal combustion driven pumping system and variable torque transmission

Claim 2

In an internal combustion driven fluid pumping apparatus for accumulating fluid pressure to be applied against a load, including a two-stroke combustion cylinder having a first reciprocable piston therein, a compression cylinder having a second reciprocable piston therein drivingly connected to said first piston, and accumulator means for storing fluid pressure pumped into said accumulator means by the energy of combustion occurring in said combustion cylinder, the improvement comprising: means for operating said combustion cylinder only in response to the pressure in said accumulator means falling below a predetermined level; means for operating said first and second pistons at the same substantially constant speed within the combustion and compression cylinders, respectively, during each stroke; and means for regulating said speed of said second piston to regulate the rate of fluid flow from said compression cylinder into said accumulator means.

Claim 3

In a method of pumping fluid into an accumulator including the steps of compressing and burning fuel and air in an internal combustion cylinder, having a first piston, to drive a compression cylinder, having a second piston, during a power stroke, to pump fluid into said accumulator, the improvement comprising the steps of: operating said combustion cylinder only in response to the pressure in said accumulator falling below a predetermined level by transmitting fluid under pressure from said accumulator to said compression cylinder at a pressure less than the pressure in said accumulator to compress fuel and air in said combustion cylinder; and operating said first and second pistons at the same substantially constant speed within the combustion and compression cylinders, respectively, during each stroke.

Claim 4

In a method of pumping fluid into an accumulator including the steps of compressing and burning fuel and air in an internal combustion cylinder, having a first piston, to drive a compression cylinder, having a second piston, during a power stroke, to pump fluid into said accumulator, the improvement comprising the steps of: operating said combustion cylinder only in response to the pressure in said accumulator falling below a predetermined level by transmitting fluid under pressure from said accumulator to said compression cylinder at a pressure less than the pressure in said accumulator to compress fuel and air in said combustion cylinder; and operating said first and second pistons at the same substantially constant speed within the combustion and compression cylinders, respectively, during each stroke.

Claim 5

The method of claim 2, further comprising the step of relieving fluid pressure in said compression cylinder responsive to said power stroke not being completed within a predetermined period of time.

Claim 6

The method of claim 2, further comprising the step of regulating the speed of movement of said second piston to regulate the rate of fluid flow from said compression cylinder into said accumulator.

Claim 7

An internal combustion engine and fluid pump comprising: a combustion cylinder including a first reciprocable piston therein; means for admitting combustible gases into said combustion cylinder; a compression cylinder including a second reciprocable piston therein drivingly linked to said first piston; accumulator means containing said fluid and connected by a fluid path to said compression cylinder; means for sensing the pressure of fluid in said accumulator means; control means responsive to the pressure of fluid in said accumulator means falling below a predetermined level for forcing fluid into said compression cylinder to move said second piston from a starting position and thereby to move said first piston within said combustion cylinder to compress combustion gases in said combustion cylinder; said control means comprising a drive cylinder including a third reciprocable piston therein; drive valve means for selectively admitting pressurized fluid into said drive cylinder; an amplifier cylinder having a cross-sectional area greater than said drive cylinder and including a fourth reciprocable piston therein drivingly linked to said third piston; amplifier input valve means for filling said amplifier cylinder from a reservoir and emptying said drive cylinder when said drive cylinder is not connected to pressurized fluid; amplifier output valve means for connecting said amplifier cylinder to said fluid path when said drive cylinder is connected to said pressurized fluid; and check valve means in said fluid path between said accumulator means and said compression cylinder for preventing escape from said accumulator means of fluid forced into said accumulator means by said second piston upon combustion within said combustion cylinder.

Claim 8

An internal combustion engine and fluid pump comprising: a combustion cylinder including a first reciprocable piston therein; means for admitting combustible gases into said combustion cylinder; a compression cylinder including a second reciprocable piston therein drivingly linked to said first piston; accumulator means containing said fluid and connected by a fluid path to said compression cylinder; means for sensing the pressure of fluid in said accumulator means; control means responsive to the pressure of fluid in said accumulator means falling below a predetermined level for forcing fluid into said compression cylinder to move said second piston from a starting position and thereby to move said first piston within said combustion cylinder to compress combustion gases in said combustion cylinder; said control means comprising a drive cylinder including a third reciprocable piston therein; drive valve means for selectively admitting pressurized fluid into said drive cylinder; an amplifier cylinder having a cross-sectional area greater than said drive cylinder and including a fourth reciprocable piston therein drivingly linked to said third piston; amplifier input valve means for filling said amplifier cylinder from a reservoir and emptying said drive cylinder when said drive cylinder is not connected to pressurized fluid; amplifier output valve means for connecting said amplifier cylinder to said fluid path when said drive cylinder is connected to said pressurized fluid; and check valve means in said fluid path between said accumulator means and said compression cylinder for preventing escape from said accumulator means of fluid forced into said accumulator means by said second piston upon combustion within said combustion cylinder.

Claim 9

An internal combustion engine and fluid pump comprising: a combustion cylinder including a first reciprocable piston therein; means for admitting combustible gases into said combustion cylinder; a compression cylinder including a second reciprocable piston therein drivingly linked to said first piston; accumlator means containing said fluid and connected by a fluid path to said compression cylinder; means for sensing the pressure of fluid in said accumulator means; control means responsive to the pressure of fluid in said accumulator means falling below a predetermined level for forcing fluid into said compression cylinder to move said second piston from a starting position and thereby to move said first piston within said combustion cylinder to compress combustible gases in said combustion cylinder; check valve means in said fluid path between said accumulator means and said compression cylinder for preventing escape from said accumulator means of fluid forced into said accumulator means by said second piston upon combustion within said combustion cylinder; means biasing said first and second pistons toward said starting position; means for sensing return of said first and second pistons to said starting position following combustion in said combustion cylinder; and means responsive to said first and second piston being absent from said starting position for longer than a predetermined period of time, for relieving the pressure of said fluid in said compression cylinder.

Claim 10

An internal combustion engine and fluid pump comprising: a combustion cylinder including a first reciprocable piston therein; means for admitting combustible gases into said combustion cylinder; a compression cylinder including a second reciprocable piston therein drivingly linked to said first piston; accumlator means containing said fluid and connected by a fluid path to said compression cylinder; means for sensing the pressure of fluid in said accumulator means; control means responsive to the pressure of fluid in said accumulator means falling below a predetermined level for forcing fluid into said compression cylinder to move said second piston from a starting position and thereby to move said first piston within said combustion cylinder to compress combustible gases in said combustion cylinder; check valve means in said fluid path between said accumulator means and said compression cylinder for preventing escape from said accumulator means of fluid forced into said accumulator means by said second piston upon combustion within said combustion cylinder; means biasing said first and second pistons toward said starting position; means for sensing return of said first and second pistons to said starting position following combustion in said combustion cylinder; and means responsive to said first and second piston being absent from said starting position for longer than a predetermined period of time, for relieving the pressure of said fluid in said compression cylinder.

Claim 11

An internal combustion engine and fluid pump comprising: a combustion cylinder including a first reciprocable piston therein; means for admitting combustible gases into said combustion cylinder; a compression cylinder including a second recirpocable piston therein drivingly linked to said first piston; accumulator means containing said fluid and connected by a fluid path to said compression cylinder; means for sensing the pressure of fluid in said accumulator means; control means responsive to the pressure of fluid in said accumulator means falling below a predetermine level for forcing fluid into said compression cylinder to move said second piston from a starting position and thereby to move said first piston within said combustion cylinder to compress combustible gases in said combustion cylinder; check valve means in said fluid path between said accumulator means and said compression cylinder for preventing escape from said accumulator means of fluid forced into said accumulator means by said second piston upon combustion within said combustion cylinder; position detection means for providing a ready signal when said first and second pistons are in said starting position, said control means being responsive to said pressure of fluid in said accumulator and to presence of said ready signal; and stroke adjusting means for varying the location along the path of travel of said first and secod pistons at which said ready signal is provided.

Claim 12

An internal combustion engine and fluid pump comprising: a combustion cylinder including a first reciprocable piston therein; means for admitting combustible gases into said combustion cylinder; a compression cylinder including a second recirpocable piston therein drivingly linked to said first piston; accumulator means containing said fluid and connected by a fluid path to said compression cylinder; means for sensing the pressure of fluid in said accumulator means; control means responsive to the pressure of fluid in said accumulator means falling below a predetermine level for forcing fluid into said compression cylinder to move said second piston from a starting position and thereby to move said first piston within said combustion cylinder to compress combustible gases in said combustion cylinder; check valve means in said fluid path between said accumulator means and said compression cylinder for preventing escape from said accumulator means of fluid forced into said accumulator means by said second piston upon combustion within said combustion cylinder; position detection means for providing a ready signal when said first and second pistons are in said starting position, said control means being responsive to said pressure of fluid in said accumulator and to presence of said ready signal; and stroke adjusting means for varying the location along the path of travel of said first and secod pistons at which said ready signal is provided.

Claim 13

The apparatus of claim 7, wherein said stroke adjusting means varies the location at which said ready signal is received responsive to the pressure of fluid in said accumulator means.

Claim 14

An internal combustion engine and fluid pump comprising: a combustion cylinder including a first reciprocable piston therein; means for admitting combustible gases into said combustion cylinder; a compression cylinder including a second reciprocable piston therein drivingly linked to said first piston; accumulator means containing said fluid and connected by a fluid path to said compression cylinder; means for sensing the pressure of fluid in said accumulator means; control means responsive to the pressure of fluid in said accumulator means falling below a predetermined level for forcing fluid into said compression cylinder to move said second piston from a starting position and thereby to move said first piston within said combustion cylinder to compress combustible gases in said combustion cylinder; and check valve means in said fluid path between said accumulator means and said compression cylinder for preventing escape from said accumulator means of fluid forced into said accumulator means by said second piston upon combustion within said combustion cylinder; said combustion cylinder comprising: cylinder valve means for selectively providing fluid communicating between the interior and exterior of said combustion cylinder; means for biasing said cylinder valve means into a first position; a valve operating cylinder including a reciprocable piston therein drivingly connected to said cylinder valve means; and valve control means for selectively connecting said accumulator means to said valve operating cylinder to admit pressurized fluid into said operating cylinder to move said cylinder valve means into a second position, and for alternately disconnecting said accumulator means from said cylinder valve means to allow said biasing means to return said cylinder valve means to its first position.

Claim 15

An internal combustion engine and fluid pump comprising: a combustion cylinder including a first reciprocable piston therein; means for admitting combustible gases into said combustion cylinder; a compression cylinder including a second reciprocable piston therein drivingly linked to said first piston; accumulator means containing said fluid and connected by a fluid path to said compression cylinder; means for sensing the pressure of fluid in said accumulator means; control means responsive to the pressure of fluid in said accumulator means falling below a predetermined level for forcing fluid into said compression cylinder to move said second piston from a starting position and thereby to move said first piston within said combustion cylinder to compress combustible gases in said combustion cylinder; and check valve means in said fluid path between said accumulator means and said compression cylinder for preventing escape from said accumulator means of fluid forced into said accumulator means by said second piston upon combustion within said combustion cylinder; said combustion cylinder comprising: cylinder valve means for selectively providing fluid communicating between the interior and exterior of said combustion cylinder; means for biasing said cylinder valve means into a first position; a valve operating cylinder including a reciprocable piston therein drivingly connected to said cylinder valve means; and valve control means for selectively connecting said accumulator means to said valve operating cylinder to admit pressurized fluid into said operating cylinder to move said cylinder valve means into a second position, and for alternately disconnecting said accumulator means from said cylinder valve means to allow said biasing means to return said cylinder valve means to its first position.

Claim 16

An internal combustion engine and fluid pump comprising: a combustion cylinder including a first reciprocable piston therein; means for admitting combustible gases into said combustion cylinder; a compression cylinder including a second reciprocable piston therein drivingly linked to said first piston; accumulator means containing said fluid and connected by a fluid path to said compression cylinder; means for sensing the pressure of fluid in said accumulator means; control means responsive to the pressure of fluid in said accumulator means falling below a predetermined level for forcing fluid into said compression cylinder to move said second piston from a starting position and thereby to move said first piston within said combustion cylinder to compress combustible gases in said combustion cylinder; check valve means in said fluid path between said accumulator means and said compression cylinder for preventing escape from said accumulator means of fluid forced into said accumulator means by said second piston upon combustion within said combustion cylinder; and means for limiting the flow rate of fluid being forced into said accumulator means by said second piston by transforming a portion of the energy of combustion in said combustion cylinder into kinetic energy of a mass mounted to move with said first and second pistons.

Claim 17

An internal combustion engine and fluid pump comprising: a combustion cylinder including a first reciprocable piston therein; means for admitting combustible gases into said combustion cylinder; a compression cylinder including a second reciprocable piston therein drivingly linked to said first piston; accumulator means containing said fluid and connected by a fluid path to said compression cylinder; means for sensing the pressure of fluid in said accumulator means; control means responsive to the pressure of fluid in said accumulator means falling below a predetermined level for forcing fluid into said compression cylinder to move said second piston from a starting position and thereby to move said first piston within said combustion cylinder to compress combustible gases in said combustion cylinder; check valve means in said fluid path between said accumulator means and said compression cylinder for preventing escape from said accumulator means of fluid forced into said accumulator means by said second piston upon combustion within said combustion cylinder; and means for limiting the flow rate of fluid being forced into said accumulator means by said second piston by transforming a portion of the energy of combustion in said combustion cylinder into kinetic energy of a mass mounted to move with said first and second pistons.

Claim 18

An internal combustion engine and fluid pump comprising: a combustion cylinder including a first reciprocable piston therein; means for admitting combustible gases into said combustion cylinder; a compression cylinder including a second reciprocable piston therein drivingly linked to said first piston; accumulator means containing said fluid and connected by a fluid path to said compression cylinder; means for sensing the pressure of fluid in said accumulator means; control means responsive to the pressure of fluid in said accumulator means falling below a predetermined level for forcing fluid into said compression cylinder to move said second piston from a starting position and thereby to move said first piston within said combustion cylinder to compress combustible gases in said combustion cylinder; check valve means in said fluid path between said accumulator means and said compression cylinder for preventing escape from said accumulator means of fluid forced into said accumulator means by said second piston upon combustion within said combustion cylinder; and an auxiliary compression cylinder including a reciprocable piston therein drivingly connected to a cam follower; a cam surface mounted for movement with said first and second pistons and engaging said cam follower; and fluid conduit means connecting said auxiliary compression cylinder to said accumulator means; said cam surface being operative to drive said auxiliary compression cylinder to force fluid into said accumulator means upon combustion within said combustion cylinder.

Claim 19

An internal combustion engine and fluid pump comprising: a combustion cylinder including a first reciprocable piston therein; means for admitting combustible gases into said combustion cylinder; a compression cylinder including a second reciprocable piston therein drivingly linked to said first piston; accumulator means containing said fluid and connected by a fluid path to said compression cylinder; means for sensing the pressure of fluid in said accumulator means; control means responsive to the pressure of fluid in said accumulator means falling below a predetermined level for forcing fluid into said compression cylinder to move said second piston from a starting position and thereby to move said first piston within said combustion cylinder to compress combustible gases in said combustion cylinder; check valve means in said fluid path between said accumulator means and said compression cylinder for preventing escape from said accumulator means of fluid forced into said accumulator means by said second piston upon combustion within said combustion cylinder; and an auxiliary compression cylinder including a reciprocable piston therein drivingly connected to a cam follower; a cam surface mounted for movement with said first and second pistons and engaging said cam follower; and fluid conduit means connecting said auxiliary compression cylinder to said accumulator means; said cam surface being operative to drive said auxiliary compression cylinder to force fluid into said accumulator means upon combustion within said combustion cylinder.

Claim 20

An internal combustion engine and fluid pump comprising: a combustion cylinder including a first reciprocable piston therein; means for admitting combustible gases into said combustion cylinder; a compression cylinder including a second reciprocable piston therein drivingly linked to said first piston; accumulator means containing said fluid and connected by a fluid path to said compression cylinder; means for sensing the pressure of fluid in said accumulator means; control means responsive to the pressure of fluid in said accumulator means falling below a predetermined level for forcing fluid into said compression cylinder to move said second piston from a starting position and thereby to move said first piston within said combustion cylinder to compress combustible gases in said combustion cylinder; check valve means in said fluid path between said accumulator means and said compression cylinder for preventing escape from said accumulator means of fluid forced into said accumulator means by said second piston upon combustion within said combustion cylinder; and means for connecting said accumulator means to said load, comprising: a variable column hydraulic pump including a pump shaft drivingly connected to said load; a hydraulic motor including a motor shaft drivingly connected to said pump shaft; a first fluid conduit connecting said accumulator means to a high pressure inlet of said motor; a second fluid conduit connecting a low pressure outlet of said motor to a low pressure inlet of said pump; and means for varying the output of said pump while maintaining the torque of said motor at a substantially constant rate, whereby the torque transmitted to the load through said pump shaft is controlled by controlling the output of said pump.

Claim 21

An internal combustion engine and fluid pump comprising: a combustion cylinder including a first reciprocable piston therein; means for admitting combustible gases into said combustion cylinder; a compression cylinder including a second reciprocable piston therein drivingly linked to said first piston; accumulator means containing said fluid and connected by a fluid path to said compression cylinder; means for sensing the pressure of fluid in said accumulator means; control means responsive to the pressure of fluid in said accumulator means falling below a predetermined level for forcing fluid into said compression cylinder to move said second piston from a starting position and thereby to move said first piston within said combustion cylinder to compress combustible gases in said combustion cylinder; check valve means in said fluid path between said accumulator means and said compression cylinder for preventing escape from said accumulator means of fluid forced into said accumulator means by said second piston upon combustion within said combustion cylinder; and means for connecting said accumulator means to said load, comprising: a variable column hydraulic pump including a pump shaft drivingly connected to said load; a hydraulic motor including a motor shaft drivingly connected to said pump shaft; a first fluid conduit connecting said accumulator means to a high pressure inlet of said motor; a second fluid conduit connecting a low pressure outlet of said motor to a low pressure inlet of said pump; and means for varying the output of said pump while maintaining the torque of said motor at a substantially constant rate, whereby the torque transmitted to the load through said pump shaft is controlled by controlling the output of said pump.

Claim 22

An internal combustion engine and fluid pump comprising: a combustion cylinder including a first reciprocable piston therein; means for admitting combustible gases into said combustion cylinder; a compression cylinder including a second reciprocable piston therein drivingly linked to said first piston; accumulator means containing said fluid and connected by a fluid path to said compression cylinder; means for sensing the pressure of fluid in said accumulator means; control means responsive to the pressure of fluid in said accumulator means falling below a predetermined level utilizing fluid pressure from said accumulator means for to force fluid into said compression cylinder to move said second piston from a starting position and thereby to move said first piston within said combustion cylinder to compress combustible gases in said combustion cylinder; and check valve means in said fluid path between said accumulator means and said compression cylinder for preventing escape from said accumulator means of fluid forced into said accumulator means by said second piston upon combustion within said combustion cylinder.

Claim 23

An internal combustion engine and fluid pump comprising: a combustion cylinder including a first reciprocable piston therein; means for admitting combustible gases into said combustion cylinder; a compression cylinder including a second reciprocable piston therein drivingly linked to said first piston; accumulator means containing said fluid and connected by a fluid path to said compression cylinder; means for sensing the pressure of fluid in said accumulator means; control means responsive to the pressure of fluid in said accumulator means falling below a predetermined level utilizing fluid pressure from said accumulator means for to force fluid into said compression cylinder to move said second piston from a starting position and thereby to move said first piston within said combustion cylinder to compress combustible gases in said combustion cylinder; and check valve means in said fluid path between said accumulator means and said compression cylinder for preventing escape from said accumulator means of fluid forced into said accumulator means by said second piston upon combustion within said combustion cylinder.

Claim 24

The apparatus of claim 13, wherein said control means forces fluid into said compression cylinder by forcing fluid into said fluid path between said check valve means and said compression cylinder at a pressure less than the pressure of fluid in said accumulator means and sufficient to compress and ignite combustible gases in said combustion cylinder.

Claim 25

The apparatus of claim 13, wherein said control means comprises a drive cylinder including a third reciprocable piston therein; drive valve means for selectively connecting said accumulator means to said drive cylinder to admit pressurized fluid into said drive cylinder; an amplifier cylinder having a cross-sectional area greater than said drive cylinder and including a fourth reciprocable piston therein drivingly linked to said third piston; amplifier input valve means for filling said amplifier cylinder from a reservoir and emptying said drive cylinder when said drive cylinder is not connected to said accumulator means; and amplifier output valve means for connecting said amplifier cylinder to said fluid path when said drive cylinder is connected to said accumulator means.

Claim 26

The apparatus of claim 13, further comprising a mass mounted for travel with said first and second pistons, said mass being sufficient to smooth the motion of said pistons responsive to combustion in said combustion cylinder.

Claim 27

The apparatus of claim 13, further comprising starting means, responsive to the pressure of fluid in said accumulator means being less than the operating pressure required to ignite combustible gases in said combustion cylinder, for pumping fluid from a reservoir into said accumulator means until the pressure therein reaches said operating pressure.

Claim 28

The apparatus of claim 13, wherein said first and second pistons are drivingly connected by a rigid, linear connecting rod.

Claim 29

The apparatus of claim 13, further comprising means for limiting the flow rate of fluid being forced into said accumulator means by said second piston by transforming a portion of the energy of combustion in said combustion cylinder into kinetic energy of a mass mounted to move with said first and second pistons.

Claim 30

The apparatus of claim 13, wherein said combustion cylinder comprises: combustion valve means for selectively providing fluid communication between the interior and exterior of said combustion cylinder; means for biasing said combustion valve means into a closed position; a combustion valve operating cylinder including a reciprocable piston therein drivingly connected to said combustion valve means; and combustion control valve means for selectively connecting said accumulator means to said combustion valve operating cylinder to admit pressurized fluid into said operating cylinder to open said combustion valve means, and for alternately disconnecting said accumulator means from said combustion valve means to allow said biasing means to close said combustion valve means.

Claim 31

The apparatus of claim 13 further comprising means biasing said first and second pistons toward said starting position; means for sensing return of said first and second pistons to said starting position following combustion in said combustion cylinder; and means responsive to said first and second piston being absent from said starting position for longer than a predetermined period of time, for relieving the pressure of said fluid in said compression cylinder.

Claim 32

The apparatus of claim 21, wherein said means for relieving the pressure of said fluid in said compression cylinder comprises selectively operable valve means for connecting said compression cylinder to a reservoir.

Claim 33

The apparatus of claim 13, wherein said combustion cylinder comprises: an outwardly opening intake valve; spring means urging said intake valve toward its open position; an intake valve operating cylinder including a fifth reciprocable piston therein drivingly connected to said intake valve; and intake control valve means for selectively connecting said accumulator means to said intake valve operating cylinder to admit pressurized fluid into said input valve operating cylinder and to thereby hold said intake valve in a closed position against said spring means, and alternatively disconnecting said accumulator means from said intake valve operating cylinder to allow said spring means to open said intake valve.

Claim 34

The apparatus of claim 23 wherein said combustion cylinder further comprises; an air drive cylinder including a sixth reciprocable piston therein; air drive valve means for selectively connecting said accumulator means to said air drive cylinder to admit pressurized fluid into said air drive cylinder; an air delivery cylinder including a seventh reciprocable piston therein drivingly connected to said sixth piston; air conduit means including said intake valve, connecting said air delivery cylinder to said combustion cylinder; said air drive valve means being operative to pressurize said air drive cylinder so as to cause said seventh piston to eject air from said air delivery cylinder through said air conduit means into said combustion cylinder when said intake valve is open.

Claim 35

The apparatus of claim 13, further comprising means for injecting water into said combustion cylinder responsive to the temperature of said combustion cylinder being greater than a predetermined level.

Claim 36

The apparatus of claim 25, further comprising a layer of insulation surrounding said combustion cylinder.

Claim 37

The apparatus of claim 13, further comprising: an auxiliary compression cylinder including a reciprocable piston therein drivingly connected to a cam follower; a cam surface mounted for movement with said first and second pistons and engaging said cam follower; and fluid conduit means connecting said auxiliary compression cylinder to said accumulator means; said cam surface being operative to drive said auxiliary compression cylinder to force fluid into said accumulator means upon combustion within said combustion cylinder.

Claim 38

The apparatus of claim 27, wherein said cam surface slopes away from the path of travel of said first and second pistons as said cam surface extends from said compression cylinder toward said combustion cylinder, and is profiled to match the pressure of gases in said combustion cylinder during combustion therein.

Claim 39

The apparatus of claim 28, wherein said cam surface includes an initial steeply sloping segment, an intermediate gently sloping segment, and a final steeply sloping segment.

Claim 40

The apparatus of claim 13, further comprising means for connecting said accumulator means to a load, comprising: a variable volume hydraulic pump including a pump shaft drivingly connected to said load; a hydraulic motor including a motor shaft drivingly connected to said pump shaft; a first fluid conduit connecting said accumulator means to a high pressure inlet of said motor; a second fluid conduit connecting a low pressure outlet of said motor to a low pressure inlet of said pump; and means for varying the output of said pump while maintaining the torque of said motor at a substantially constant rate, whereby the torque transmitted to the load through said pump shaft is controlled by controlling the output of said pump.

Claim 41

The apparatus of claim 30, further comprising a third fluid conduit connecting a high pressure outlet of said pump to said first fluid conduit, said third fluid conduit including check valve means for preventing flow from said first fluid conduit to said pump.

Claim 42

The apparatus of claim 13, further comprising: position detection means for providing a ready signal when said first and second pistons are in said starting position, said control means being responsive to said pressure of fluid in said accumulator and to presence of said ready signal; and stroke adjusting means for varying the location along the path of travel of said first and second pistons at which said ready signal is provided.

Claim 43

The apparatus of claim 32, wherein said stroke adjusting means varies the location at which said ready signal is received responsive to the pressure of fluid in said accumulator means.

Claim 44

The apparatus of claim 33, wherein said stroke adjusting means shortens the distance travelled by said first and second pistons responsive to an increase in the presence of fluid in said accumulator means, and lengthens the distance travelled by said first and second pistons responsive to a decrease in the pressure of fluid in said accumulator means.

Claim 45

The apparatus of claim 33, wherein said stroke adjusting means varies the location at which said ready signal is provided by varying the location of said position detection means along the path of travel of said first and second pistons.