Abstract: A parallel two-wheeled vehicle including a braking mechanism to directly brake two wheels that includes: a body; a pair of drive units coaxially mounted to the body; a T-shaped handle to be gripped by a passenger; a longitudinal inclination detecting device of the body; and a brake lever. A brake detecting device detects operational information of the brake lever. The body includes: a vehicle speed detecting device to determine a vehicle speed based on a relative angular velocity between the body and the wheels, which is detected by the drive units and based on an angular velocity detected by the longitudinal inclination detecting device; a target speed setting device to set a target vehicle speed based on an output of each of the brake detecting device and the vehicle speed detecting device; and a stabilization control device to control the vehicle to stably follow the target angle/target angular velocity/target vehicle speed. Further, powder brakes are incorporated in the drive units, respectively.

Abstract: Systems, methods and programs are provided for a vehicle that performs braking by a regeneration brake and a friction brake. The systems, methods, and programs determine that braking by the friction brake has been performed, acquire information indicating a situation in the vicinity of the vehicle, and determine a necessary braking force required for responding to the situation in the vicinity of the vehicle. When it is determined that the braking by the friction brake has been performed in a condition where the necessary braking force is less than or equal to a maximum braking force of the regeneration brake, the systems, methods, and programs, determine energy consumed by the friction brake and communicate notification information indicating the consumed energy to a driver.

Abstract: A power generation system for a surface transport vehicle having at least two wheels. The power generation system includes a primary power generation device and a secondary power generation device. A connector attaches the secondary power generation device to at least two wheels of the surface transport vehicle. The power generation system also includes a power storage unit capable of storing energy received from either the primary or secondary power generation devices. Furthermore, the power generation system includes a torque converter which is capable of transferring power from the secondary power generation device to the power storage unit.

Abstract: [OBJECT] To provide a brake control apparatus and method for controlling the brake which is capable of preventing a fluctuation of a brake pedal stroke amount when switching a regenerative braking force to a hydraulic braking force.

Abstract: An air braking system for a vehicle blends regenerative and foundation braking during low deceleration conditions in an effective and controlled manner. The braking system also includes a mechanical override that bypasses system electronics in response to an aggressive brake request such that treadle circuit pressure is sent directly to a brake relay circuit to actuate vehicle brakes.

Abstract: A method for operating a powertrain system including a torque machine coupled to a drive wheel of a vehicle includes determining a regenerative braking capacity of the powertrain system. In response to a net operator torque request including a braking torque request, a friction braking torque command to operate a friction brake system and a regenerative braking torque request for the torque machine are coincidentally generated, a torque command is generated for controlling operation of the torque machine in response to the regenerative braking torque request, and the friction braking torque command is adjusted by an amount corresponding to a difference between the braking torque request and the regenerative braking torque request.

Abstract: A torque applying device is provided for applying a driving torque to at least a pair of wheels, and a torque restraining device is provided for restraining the torque created on the wheels to be applied with the torque by the torque applying device. A friction braking device is provided for applying a braking torque to each wheel in response to operation of a brake pedal. An automatic braking control device automatically actuates the friction braking device independently of operation of the brake pedal, to apply the braking torque to each wheel. And, a torque restraining cancellation device is provided for cancelling the torque restraining operation for a time period determined in response to a vehicle speed decreasing state, after a condition for initiating the automatic braking control was fulfilled.

Abstract: A system including a calculator and a control housing including switches having a single stable position in an opened position and with a manual control member for the switches. The control member is of monostable type with automatic return into a rest position in which all switches are open. The housing includes: a single first switch controlling actuation of brakes and adapted to be closed upon an action on the control member in a first direction; a single second switch controlling release of the brakes and adapted to be closed upon an action on the control member in a second direction opposite the first direction; and a diagnosis circuit providing, according to the position of the control member, an analog information distinguishing between a system activated state in which one of the first and second switches is closed, a system deactivated state in which the first and second switches are open, and malfunction states.

Abstract: A computer-implemented method includes identifying a representation of a feature of an animated character by inverting an skinned representation of the feature in one position. The inversion includes a non-linear inversion of the skinned representation of the feature. The method also includes skinning the identified feature representation to produce the animated character in another position.

Abstract: A system and method for controlling torque in a hybrid electric vehicle. The system provides a regenerative braking torque with an electrical machine when a level of braking torque indicated by actuation of a brake control device exceeds a level of traction torque indicated by actuation of an acceleration control device. The regenerative braking torque is supplemented by a friction braking system when the braking torque requested by a vehicle operator exceeds a maximum regenerative braking capacity of the electrical machine.

Abstract: A braking controller is equipped to provide braking force distribution of the required total braking force, to distribute the required total braking force by regeneration distribution. The regeneration distribution is required to be within a rear-wheel dominant range, in which the distribution ratio is inclined toward the rear-wheels when compared with an ideal distribution line that provides distribution enabling the front and rear wheels to simultaneously lock, as well as within a range that is not greater than a rear-wheel locking limit enabling the rear wheels to lock in relation to a road-surface friction coefficient upon braking. A rear-wheel braking force change ratio, which is a change ratio of the rear-wheel braking force with regard to a change of the front-wheel braking force associated with the change of the required total braking force, is required to always be positive.

Abstract: Disclosed herein is a method of controlling an Anti-lock Brake system (ABS) of an electronic brake, which is driven using an electric motor. In ABS braking in which braking and braking-release motions are repeated according to a wheel slip value, the electric motor is controlled in a re-braking section to link a position of a brake pad with a change in wheel speed, to enhance ABS control responsiveness and to reduce stopping distance with maximized brake force.

Abstract: A brake system in an electric drive dump truck. The electric drive dump truck has a generator 11 driven by an engine 10 and traveling motors 13L, 13R driven with electric power generated by the generator 11. Hydraulic brakes 20L, 20R, 21L, 20R are operated by brake pedal 18. An oil pressure sensor 22 detects hydraulic fluid pressure produced in accordance with the amount of depression of the brake pedal 18 and a control unit 14 controls the traveling motors 13L, 13R so as to operate them as generator-type retarders when the hydraulic fluid pressure P detected by the oil pressure sensor 22 is not smaller than a predetermined value P1.

Abstract: A system and method of controlling an automotive vehicle includes generating a reverse direction signal corresponding to a reverse direction of the vehicle and generating brake-steer in response to the reverse direction signal.

Abstract: Disclosed is a regenerative braking system capable of minimizing uncomfortable feeling during the braking operation while improving responsiveness and control performance by performing the braking operation using an electric motor. An electro-mechanical braking system is used when braking a rear wheel or front and rear wheels, so variable frictional braking is achieved, thereby maximizing the recovery rate of the regenerative energy.

Abstract: A method for operating a vehicle brake system and a corresponding vehicle brake system, particularly for motor vehicles. The vehicle wheels of the motor vehicle associated with an axle are at least partially driven by ‘WV’ an electric motor that can be operated as a generator during regeneration of braking energy, thus exerting a braking regeneration el torque on the respective axle. To prevent overbraking on the rear axle, the regeneration torque acting on at least one rear axle (HA) is limited such that the slippage present on the at least one vehicle wheel of the rear axle (HA) does not exceed or only negligibly exceeds a first slippage threshold individually associated with the respective vehicle wheel.

Abstract: A controller for controlling braking of a wheel of a vehicle. The controller includes a first connection to a friction brake, a second connection to a motor/generator, a third connection to a plurality of sensors, and a fuzzy logic module. The motor/generator is configured to drive the wheel in a driving mode and to brake the wheel in a regenerative braking mode. Operating parameters of the vehicle are sensed by the plurality of sensors. The fuzzy logic module is configured to determine a stability of the vehicle and the wheel based on data from the plurality of sensors. The fuzzy logic module allocates braking force between the friction brake and the motor/generator operating in the regenerative braking mode based on the stability of the vehicle and the wheel.

Abstract: There is provide a brake control technology according to which a target hydraulic pressure is reliably achieved when a hydraulic pressure is decreased during hydraulic control and brake drag does not occur even when the target hydraulic pressure is zero. In a brake apparatus, a dead-band region is set for the target hydraulic pressure that is used in the hydraulic control. When braking control is switched from the hydraulic control to regenerative control in cooperative braking control, residual pressure reduction control is executed. In the residual pressure reduction control, the target hydraulic pressure is set to a value that is lower than zero to which the hydraulic pressure should be brought.

Abstract: In a method for recovering energy in a braking process of a hybrid vehicle which has an internal combustion engine and an electric drive, as well as a hydraulic or pneumatic braking system, the exploitation of the electric drive is able to be optimized if the braking system includes at least one pressure reduction valve, using which the braking pressure exerted by the driver is able to be reduced as a function of the deceleration proportion of the electric machine.

Abstract: A vehicular braking apparatus includes an electric motor that generates a wheel driving force or a regenerative wheel braking force and also includes a mechanical wheel braking force generating device, an external braking force generating device, and a braking control device. The mechanical wheel braking force generating device includes a working fluid pressure adjusting unit that generates a mechanical wheel braking force by transmitting the pressure of a working fluid. The external braking force generating device applies an external braking force other than a regenerative vehicle braking force generated by the electric motor and a mechanical vehicle braking force generated by the mechanical wheel braking force generating device, to a vehicle. The braking control device compensates a braking force by an external braking force in order to satisfy a requested vehicle braking force by a driver when the conversion efficiency of the electric motor to electrical energy is decreased.

Abstract: A system for providing regenerative and friction braking in a vehicle includes a brake controller for determining a desired rate of deceleration from sensor outputs which are responsive to inputs from an operator of a vehicle and a regenerative braking system operatively connected with the brake controller. A brake monitor receives the sensor inputs from the operator of the vehicle and determines an audit range of deceleration for the vehicle. If the audit range of deceleration of the vehicle is not subsequently sensed, the vehicle's driver will be alerted.

Abstract: A control system (11) for a vehicle (10) includes vehicle dynamics sensors (35-47) providing a vehicle dynamics signal. Tire monitoring system sensors (20) in each wheel generate tire signals including temperature, pressure and acceleration data. A controller (26) communicates with the tire monitoring system sensors (20) and at least one vehicle dynamics sensor, and generates a brake signal as a function of the multi-axis acceleration data of the tire signals. The brake signal is transmitted to a brake system (64) to apply a brake torque in response to the brake signal.

Abstract: In a hybrid vehicle 20, when an ECO switch 88 is “on” when a brake demand operation is performed by a driver, a target regeneration distribution rate d is set using an ECO mode regeneration distribution rate setting map that gives priority to energy efficiency in comparison to a normal regeneration distribution rate setting map that is used when the ECO switch 88 is “off” and a braking force demand BF* that is based on the brake demand operation of the driver (S150), and a motor MG2 and a brake unit 90 are controlled so that the braking force demand BF* is obtained based on the target regeneration distribution rate d (S160 to S230).

Abstract: A fully electrically controlled electric braking system is provided for a road vehicle fitted with wheels (1). Each of the wheels is connected for rotation to at least one rotary electric machine (2) specific thereto, with at least one electronic wheel control module (23) controlling the electric machine(s) (2) of that wheel. Each electronic wheel control module (23) makes it possible to impart selectively to a corresponding wheel a control torque of determined amplitude and sign, in such a way that the corresponding wheel imparts to the vehicle a drive force or a braking force in accordance with the control torque. The system includes a central unit (3) for managing vehicle displacement, the central unit (3) controlling all the electronic wheel control modules (23). The central unit (3) has a vehicle braking mode activated by a vehicle braking control signal having a given amplitude representing a total desired braking force for the fully electrically controlled wheels.

Abstract: A traction control method is provided for dynamically maintaining safe driving traction between a tire (12) and a driving surface in a decelerating motor vehicle (10) through a modulated braking device (18, 24). The method monitors the acceleration response of a tire (12) to a torque change induced by modulation of a braking device (18, 24). Observation of the acceleration profile over time is used to determine whether additional braking torque or pressure can be applied without causing the tire (12) to slip. A Traction Reserve value is computed through observing the acceleration trend of the tire (12) over time after a single change in torque, whether that change is accomplished as an increase or a decrease.

Abstract: A regenerative braking system for a vehicle, motorized or otherwise, that captures and stores the braking energy of the vehicle through the mechanical compression of a volume of pressurized gas contained in one or more onboard gas springs. This stored energy can be selectively released by the driver to assist with the acceleration of the vehicle from a stopped or moving condition. The compression of the volume of gas is accomplished by the insertion of a plunger into the cylinder of a gas spring by a mechanical spooling cable arrangement powered by the rotative braking of the vehicle. The release of the stored energy is accomplished by the withdrawal of the piston which acts through the spooling cable arrangement to transmit torque to the vehicle's drive train. The system can be implemented in various motorized or non-motorized vehicles.

Abstract: Methods, systems, and program products for adjusting regenerative braking torque in a vehicle having wheels and a regenerative braking system providing the regenerative braking torque are provided. A deceleration of the vehicle is determined. A wheel slip of the wheels is determined. The regenerative braking torque is adjusted for the regenerative braking system using the deceleration and the wheel slip.

Abstract: Disclosed is a method for controlling a brake system (1) of a motor vehicle, which includes an electric generator (4) and a number of hydraulic, electronically controllable friction brakes (2) being allocated to axles of the motor vehicle, and the brake torque of which is composed of the brake torque of the generator (4) and the brake torque of the friction brakes (2), is intended to safeguard great brake comfort of the brake system (1). To this end, a number of friction brakes (2) are connected only when the total nominal brake torque exceeds the total actual brake torque by a selected maximum brake torque difference.

Abstract: A brake system of a vehicle with a regenerative braking function, such as a hybrid electric vehicle. A regenerative braking hydraulic pressure line connects a master cylinder with a wheel cylinder. A regenerative control valve opens and closes the regenerative braking hydraulic pressure line. A proportional control valve is disposed in the regenerative braking hydraulic pressure line. The proportional control valve includes a spool, and output characteristics of the proportional control valve vary in response to an amount of pressure applied to the spool. A spool operator changes the amount of pressure applied to the spool.

Abstract: A method is provided for controlling the braking of a vehicle that has a first set of friction brakes for applying a first apply brake force to a first set of wheels and a second set of friction brakes for applying a second brake apply force to a second set of wheels. A powertrain assembly is coupled to the second set of wheels. The powertrain assembly includes a regenerative braking unit capable of recapturing kinetic energy from the second set of wheels. The vehicle is braked in a first phase of control using regenerative braking to brake the second set of wheels to achieve up to a first value of braking. The vehicle is braked in a second phase of control using the regenerative braking to maintain braking of the second set of wheels at the first value of braking force while selectively applying the first friction brakes to the first set of wheels up to a second value of braking.

Abstract: If a user applies a brake system while an electric vehicle that includes a battery is moving and it is confirmed that the user is not simultaneously applying the accelerator, a comparison is made between an actual deceleration and an expected deceleration corresponding to the user demand sensed by the braking system. If the actual deceleration is lower than the expected deceleration, an amount of regenerative electric current supplied to the battery is increased to better correlate the expected deceleration and the actual deceleration.

Abstract: A braking system for a wheel of a vehicle includes a regenerative brake unit and a friction brake unit. The regenerative brake unit comprises a generator including a rotor and a stator. The rotor is fixedly attached to the wheel and includes a moving friction surface integrally constructed thereon. The friction brake unit includes a stationary friction surface that engages the moving friction surface of the rotor when the friction brake unit is actuated.

Abstract: A hydraulic regenerative braking system and method for a vehicle include a variable displacement hydraulic machine operable as a pump or a motor (22). The hydraulic machine facilitates connections between some of its piston cylinders (50, 52) and a low pressure source (32), and some other of its piston cylinders (50, 52) and a high pressure source (28). The cylinders are alternately connected to the high and low pressure sources such that a pressure transition occurs during each piston stroke. By controlling where in a piston stroke the transitions occur, the power of the hydraulic machine can be modulated. The hydraulic machine is configured to effect the pressure transitions in only a portion of the cylinders at one time. This can be accomplished by asymmetrically configuring cam lobes (86, 88, 90) and fluid ports (74, 76, 78, 80, 82, 84). Staggering the pressure transitions helps to inhibit flow disturbances in the machine when it is operating at less than full displacement.

Abstract: A vehicle includes a powertrain system and a friction braking system communicating tractive torque with a driveline, the powertrain system including a torque machine, and an energy storage device connected to the torque machine, said torque machine communicating tractive torque with the driveline. A method for controlling regenerative braking and friction braking includes monitoring a vehicle operating point, determining a braking torque request, determining a regenerative braking motor torque ratio based upon the vehicle operating point wherein the regenerative braking motor torque ratio is non-linearly dependent on the vehicle operating point, and actuating the friction brake based upon the regenerative braking motor torque ratio and the braking torque request.

Abstract: Disclosed is a method for controlling a brake system (1) of a motor vehicle having an electric-regenerative brake, in particular a generator (4), and a number of hydraulic friction brakes (2) driven by at least one brake pressure generating means by way of a braking medium (B). The brake system is controlled so that the total deceleration of the brake system is composed of deceleration components of the friction brakes (2) and the electric-regenerative brake, thus achieving maximum brake comfort. The braking medium (B) is discharged into a pressure accumulator (12) when braking with an electric-regenerative brake.

Abstract: A drive system is provided for a utility vehicle and includes an alternating-current (AC) motor for providing a drive torque. An AC motor controller receives a battery voltage signal, throttle pedal position signal, brake pedal position signal, key switch signal, forward/neutral/reverse (FNR) signal, and run/tow signal indicative of the utility vehicle being configured to be driven and being configured to be towed. The AC motor controller generates an AC drive signal for the AC motor, wherein the AC drive signal is based on the battery voltage signal, throttle pedal position signal, brake pedal position signal, key switch signal, FNR signal, and run/tow signal.

Abstract: A braking energy recovery system adapted for use on a vehicle and a vehicle having such a system installed. The vehicle has an engine-transmission assembly, a driveshaft, a braking system and an auxiliary system. The energy recovery system comprises a first pump, a hydraulic accumulator and a hydraulic motor. The first pump is a variable displacement hydraulic pump. The hydraulic accumulator is connected to the first pump and is operative to store hydraulic fluid under pressure. The hydraulic motor is hydraulically connected to the accumulator to receive hydraulic fluid. The motor is adapted to drive a second hydraulic pump, which is hydraulically connected to the auxiliary system, using hydraulic energy stored in the accumulator.

Abstract: A regenerative braking coordination device has a braking operating member receiving an input from a driver in the form of an operation amount, an input shaft operable for transmitting the operation amount, and a braking force boosting device operable to generate a hydraulic braking pressure corresponding to the operation amount transmitted by the input shaft. The device further includes a hydraulic pressure braking device to generate a braking force and an operation amount absorber for absorbing the operation amount of the input shaft. The operation amount absorber includes a cylinder, a piston dividing the interior of the cylinder into first and second hydraulic chambers and an orifice connecting the first and second hydraulic chambers. The orifice can be in the piston or in a flow channel.

Abstract: A vehicle and a method for controlling regenerative braking are provided. To take advantage of regenerative braking, the maximum available regenerative braking torque is utilized for some time during a braking event. As the vehicle speed and/or powertrain torque decreases, the regenerative braking torque is controlled to deviate from the maximum. The point at which the regenerative braking torque deviates from the maximum is chosen based on the level of vehicle deceleration. The regenerative braking torque is then smoothly blended out until it reaches zero. The regenerative braking torque is brought to zero when the vehicle speed is very low, thereby eliminating the inefficiencies associated with operating a motor at a very low speed. This control of the regenerative braking torque provides a smooth and consistent feel to the vehicle operator.

Abstract: Braking control for a hybrid vehicle provides both service and regenerative mode braking for the driven wheels. A hybrid drive system is coupled to the driven wheels to provide traction power and which is capable of operating in a regenerative braking mode. The service brakes are provided by pneumatically actuated service brakes coupled to the driven wheels. Braking is initiated conventionally using an operator controlled brake actuator. A pressure regulator is placed in a pneumatic brake actuation line coupled from the operator controlled brake actuator to the pneumatically actuated service brakes for the driven wheels. The pressure regulator initially closes during braking, preventing operation of the service brakes up to the limit of the ability of the hybrid drive system to absorb torque for regenerative braking. When the torque limit for the hybrid drive system is reached, the regulator opens the actuation line progressively allowing the service brakes to supplement the hybrid drive system.

Abstract: A vehicle brake system is provided with a brake ECU serving as controlled hydraulic brake force control for executing a controlled hydraulic brake force control to decrease the rotational speed of an electric motor when at least both of a regenerative brake force and a controlled hydraulic brake force are being applied. The brake ECU decreases the rotational speed of the electric motor when the gradient of a target controlled hydraulic brake force being a controlled hydraulic pressure command value given to a hydraulic brake device is downhill or is not present. Thus, the pressured fluid supplied from a pump driven by the electric motor to be supplied to wheel cylinders of a vehicle is decreased to enhance the efficiency in utilizing the regenerative energy which an electric motor for driving the vehicle has in dependence on the stepping state of a brake pedal.

Abstract: A method for regulating the speed at which an electric vehicle descends a hill includes determining a position of a shift lever and determining if the vehicle accelerator and/or the vehicle brake are depressed. If the vehicle is in either drive or reverse and neither the vehicle accelerator nor the vehicle brake is depressed, a change in the motor speed is determined based on the current motor speed and a reference motor speed. The current braking assist is then adjusted based on the change in the motor speed such that the motor speed, and therefore the speed of the electric vehicle, remains constant as the vehicle descends the hill.

Abstract: A braking system for an electric vehicle has a first wheel having a first friction brake and an electric motor and a second having a second friction brake. A first user-actuated brake lever is coupled to the first friction brake. The first brake lever has a first sensor indicating actuation of the first brake lever. A second user-actuated brake lever is coupled to the second friction brake. The second brake lever has a second sensor indicating actuation of the second brake lever. An electronic control unit electronically coupled to the first and second sensors and the electric motor commands the electric motor to operate as a generator when at least one of the brake levers is actuated.

Abstract: A method for operating a vehicle brake system having both frictional and regenerative braking capabilities. According to one embodiment, the method monitors wheel slip at a number of vehicle wheels, evaluates individual wheel slip at a single wheel as well as collective wheel slip involving multiple wheels, compares the wheel slips to one or more speed-based thresholds that are based on vehicle speed, and uses the comparisons to help distinguish between those situations that warrant disengagement of regenerative braking operations and those that do not.

Abstract: Brake apparatus includes a transmission unit for operatively connecting a brake pedal to a master cylinder, and the transmission unit is a mechanism capable of varying a ratio between an output amount of a push rod connected to a master cylinder and an operation amount of the brake pedal. Further, the transmission unit is constructed in such a manner that, in an initial operation region of the brake pedal, a ratio of the operation amount of the brake pedal to the output amount of the push rod is set to be greater than in another operation region immediately following the initial operation region.

Abstract: A control unit of a brake apparatus includes a compensation braking force controlling device for controlling a compensation braking force in response to an operation of a brake operating member so that a characteristic of a total braking force relative to the operation of the brake operating member agrees with a predetermined target characteristic. The total braking force is a sum of the compensation braking force containing a pressurizing hydraulic braking force based upon at least the pressurization and a basic hydraulic pressure braking force based upon the basic hydraulic pressure. The compensation braking force controlling device includes: a judging device for judging whether the vehicle has stopped, and a limiting device for limiting the amount of pressurization via a pressure control valve when the judging device determines that the vehicle has stopped.

Abstract: A regenerative brake of the present invention presents a hydraulic device disposed in a front hub of a bicycle wheel. The device allows the bicycle to recapture part of the kinetic energy that would otherwise be lost when braking and make use of that power either by storing it for future use or feeding it back into a power system to be used. The hydraulic device may also be stored in a rear hub of the bicycle wheel.

Abstract: A hybrid braking system that operates in conjunction with a foundation braking system, whether an air, hydraulic, electric, mechanical or electric braking system. Recovered energy is returned to the axle wheels in a controlled manner while the vehicle is in motion and certain criteria are met so as to compensate for aerodynamic drag and rolling resistance for instance but not at a rate to accelerate or launch a vehicle.

Abstract: A regenerative brake system and a variable displacement pump/motor for use therein. Each cylinder of the pump/motor having a main piston and a second piston between which is defined a space for hydraulic fluid, and a resilient element acting on the second piston to bias it toward the main piston. Variable displacement is achieved by controlling a volume of pressurized fluid that is injected and exhausted between the main and second pistons. Brake, drive and neutral modes of operation of the pump/motor are achieved by controlling the timing (relative to a drive shaft phase) of the injection and exhaust of the fluid. Regeneration is achieved by storing pressurized fluid generated by the pump/motor in an accumulator in brake mode and using the stored pressurized fluid to power the pump/motor in drive mode.

Abstract: A regenerative brake system and a variable displacement pump/motor for use therein. Each cylinder of the pump/motor having a main piston and a second piston between which is defined a space for hydraulic fluid, and a resilient element acting on the second piston to bias it toward the main piston. Variable displacement is achieved by controlling a volume of pressurized fluid that is injected and exhausted between the main and second pistons. Brake, drive and neutral modes of operation of the pump/motor are achieved by controlling the timing (relative to a drive shaft phase) of the injection and exhaust of the fluid. Regeneration is achieved by storing pressurized fluid generated by the pump/motor in an accumulator in brake mode and using the stored pressurized fluid to power the pump/motor in drive mode.