A device is provided which performs highly-accurate control in low-torque regions while taking advantage of hydraulic pressure sealed-type hydraulic control devices. The device includes: a first characteristic (sealed pressurization) obtained by closing the on/off valve and driving an oil pump: a second characteristic (sealed depressurization) obtained by disabling drive of the oil pump and opening the on/off valve; and a third characteristic (flow-rate control) obtained by opening the on/off valve and driving the oil pump. In the process of supplying hydraulic pressure to a piston chamber in a low torque region, the device performs control according to the third characteristic. In the process of pressurizing the piston chamber in a torque region higher than the low torque region, the device performs control according to the first characteristic. In the subsequent process of depressurizing the piston chamber, the device performs control according to the second characteristic.

A device is provided which performs highly-accurate control in low-torque regions while taking advantage of hydraulic pressure sealed-type hydraulic control devices. The device includes: a first characteristic (sealed pressurization) obtained by closing the on/off valve and driving an oil pump: a second characteristic (sealed depressurization) obtained by disabling drive of the oil pump and opening the on/off valve; and a third characteristic (flow-rate control) obtained by opening the on/off valve and driving the oil pump. In the process of supplying hydraulic pressure to a piston chamber in a low torque region, the device performs control according to the third characteristic. In the process of pressurizing the piston chamber in a torque region higher than the low torque region, the device performs control according to the first characteristic. In the subsequent process of depressurizing the piston chamber, the device performs control according to the second characteristic.

A clutch assembly has a housing with a cooling path and a piston actuation path, selectively connected. In a dry clutch, a single reversible power pack selectively services both paths. In a wet clutch, a single unidirectional motor drives two pumps in unison, one servicing the cooling path and the other the piston actuation path. Inputs to a filter selectively receive solid or orifice plugs, the latter controlling the flow and pressure of coolant oil to a cooling passage matrix. Various plugs with inlets to the filter control the source of cooling oil employed by the clutch. A first implementation allows for use of the hydraulic system of the host piece of equipment or known hydraulic systems, while a second implementation provides a self-contained source of hydraulic oil, which, through the hydraulic power units described, services both the actuating system and the cooling matrix of the clutch.

A clutch assembly has a housing with a cooling path and a piston actuation path, selectively connected. In a dry clutch, a single reversible power pack selectively services both paths. In a wet clutch, a single unidirectional motor drives two pumps in unison, one servicing the cooling path and the other the piston actuation path. Inputs to a filter selectively receive solid or orifice plugs, the latter controlling the flow and pressure of coolant oil to a cooling passage matrix. Various plugs with inlets to the filter control the source of cooling oil employed by the clutch. A first implementation allows for use of the hydraulic system of the host piece of equipment or known hydraulic systems, while a second implementation provides a self-contained source of hydraulic oil, which, through the hydraulic power units described, services both the actuating system and the cooling matrix of the clutch.

In one instance, disclosed herein is a pressure modulating clutch control assembly that includes: a valve assembly configured to apply a clutch pressure to a clutch device; a pressure modulation assembly in fluid communication with the valve assembly and configured to control a maximum pressure level that the clutch pressure reaches; and a modular relief valve in fluid communication with the valve assembly and the pressure modulation assembly, the modular relief valve forming part of a hydraulic feedback loop between the valve assembly and the pressure modulation assembly, wherein the hydraulic feedback loop is configured such that an increase in a modulation pressure of a pressurized fluid within the pressure modulation assembly causes a corresponding increase in the clutch pressure until the clutch pressure reaches the maximum pressure level.