Disclosed is a clutch control reference value setting method including generating a current-hydraulic pressure model, setting a temporary VKP to a current causing a maximum difference between a model hydraulic pressure and a measured hydraulic pressure, determining that the temporary VKP is valid when a deflection amount calculated from a difference integral value acquired by integrating differences between the model hydraulic pressure and the measured hydraulic pressure while increasing the current is greater than a first reference value under a condition that the first target pressure is applied to the clutch, determining that the temporary VKP is appropriate when a deflection amount calculated from a difference integral value acquired by integrating differences between the model hydraulic pressure and the measured hydraulic pressure while increasing the current is proper under a condition that a second target pressure is applied to the clutch.

The invention relates to a hydraulic circuit having a first hydraulically actuable clutch that is closed in a rest state and a second hydraulically actuable clutch that is closed in the rest state, wherein the hydraulic circuit is configured in such a way that a hydraulic medium present in a main pressure line can be loaded with a working pressure by a pressure generating device and/or a pressure accumulator, and the hydraulic medium can be discharged for pressure dissipation via a main return line into the return reservoir. In some embodiments, the hydraulic circuit has a first distributor pressure line and a separate, first collector return line for the hydraulic supply of a first part circuit and at least one separate, second distributor pressure line and at least one separate, second collector return line for the hydraulic supply of a second part circuit, and the first clutch is assigned to the first part circuit and the second clutch is assigned to the second part circuit.

A drive force transfer device includes a multi-plate clutch that transfers a drive force using a friction force generated between a plurality of clutch plates; a housing that houses the multi-plate clutch; a piston that presses the multi-plate clutch using a hydraulic pressure of operating oil supplied to a hydraulic chamber provided in the housing; a hydraulic unit configured to supply the operating oil to the hydraulic chamber; and a control device configured to control the hydraulic unit, the control device being configured to correct a control amount for the hydraulic unit based on a result of a temperature estimation based on operation of the hydraulic unit.

A nose landing gear system is disclosed. In various embodiments, the nose landing gear system includes an electric motor; a hydraulic pump connected to the electric motor; a gearbox connected to the electric motor; and a clutch configured to mechanically couple the gearbox to a steering collar.

Disclosed is a clutch control reference value setting method including generating a current-hydraulic pressure model, setting a temporary VKP to a current causing a maximum difference between a model hydraulic pressure and a measured hydraulic pressure, determining that the temporary VKP is valid when a deflection amount calculated from a difference integral value acquired by integrating differences between the model hydraulic pressure and the measured hydraulic pressure while increasing the current is greater than a first reference value under a condition that the first target pressure is applied to the clutch, determining that the temporary VKP is appropriate when a deflection amount calculated from a difference integral value acquired by integrating differences between the model hydraulic pressure and the measured hydraulic pressure while increasing the current is proper under a condition that a second target pressure is applied to the clutch.

Systems, apparatus, and methods to control fluid associated with vehicle clutches are disclosed. A disclosed apparatus includes a drive unit assembly for a vehicle. The drive unit assembly includes a housing and a clutch in a cavity of the housing. Rotation of a drum of the clutch expels a fluid from the cavity. The apparatus also includes a vehicle controller configured to disengage the clutch via an actuator. Actuation of the actuator reduces a flow of the fluid into the cavity. The vehicle controller is also configured to maintain engagement of a vehicle transfer device operatively coupled between a vehicle transmission and the drum such that the drum continues to rotate for a time interval during which the clutch is disengaged.

A hydraulic system of a transmission includes a plurality of pressure control valves. A pilot force component and an actuating force component of additional pressure control valves are applicable in the direction of a first end position of a valve slide. A downstream pressure of the additional pressure control valves is applicable in the direction of a second end position of the valve slide. Clutch valves are configured to be brought into operative connection by a pilot-controlled valve unit with an area guiding pressure of a primary pressure circuit or with an additional valve unit. The additional valve unit is a pressure-limiting valve with a predefined pressure level adjusted upstream of the additional valve unit and connected downstream to a low-pressure area.

A utility vehicle includes: a pair of front wheels; a pair of rear wheels; at least one front wheel power source configured to drive the front wheels and not to drive the rear wheels; at least one rear wheel power source configured to drive the rear wheels and not to drive the front wheels; and a controller that controls the front wheel power source and the rear wheel power source. Upon receiving a predetermined two-wheel drive command, the controller brings the front wheel power source into a non-operative state while allowing the rear wheel power source to drive the rear wheels. Upon receiving a predetermined four-wheel drive command, the controller brings the front wheel power source into operation while allowing the rear wheel power source to drive the rear wheels.

A lubrication system for a power transmission unit that supplies oil to a starting clutch in an appropriate amount irrespective of an engagement state of the starting clutch. When the friction clutch is completely engaged or disengaged, a first control valve is brought into a low inflow rate mode, and the second control valve is brought into a low outflow rate mode. When the friction clutch is engaged while causing a slip the first control valve is brought into a high inflow rate mode, and the second control valve is brought a high outflow rate mode.

This clutch control device is provided with: a first valve; a second valve; a valve control unit configured to control the operation of each of the first valve and the second valve; an operation determination unit configured to perform an operation determination for the clutch device; and an initial operation completion determination unit which determines whether an initial operation of the clutch device has been completed. The valve control unit, if it is determined by the operation determination unit that an on-off switching process is required, subjects both the first valve and the second valve to opening-control. If it is determined by the initial operation completion determination unit that the initial operation has been completed, the valve control unit subjects the second valve to closing-control.