There is provided a hydraulic power drive unit (PDU) (30) for a transmission system (20). The hydraulic PDU comprises: a hydraulic motor (31) for converting hydraulic pressure into torque and rotation; a hydraulic brake system (32) for applying a braking force to the hydraulic motor to prevent rotation of the hydraulic motor, wherein the hydraulic brake system is biased to apply the braking force to the hydraulic motor to prevent rotation of the hydraulic motor, and configured to remove the braking force in response to a supply of hydraulic fluid; and a hydraulic circuit (33) for supplying a flow of hydraulic fluid to the hydraulic motor to pressurise and thereby operate the hydraulic motor and for supplying hydraulic fluid to the hydraulic brake system to pressurise the hydraulic brake system and thereby remove the braking force; wherein the hydraulic circuit comprises a brake supply line (39b) for supplying the hydraulic fluid to the hydraulic brake system. The brake supply line comprises a flow restricting device to restrict backflow of the hydraulic fluid in the brake supply line away from the hydraulic brake system; such that the hydraulic circuit is configured to enable depressurisation of the hydraulic motor whilst simultaneously preventing depressurisation of the hydraulic brake system thereby preventing application of the braking force.


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    Title :

    HYDRAULIC POWER DRIVE UNIT


    Additional title:

    ANTRIEBSEINHEIT MIT HYDRAULISCHER LEISTUNG
    UNITÉ D'ENTRAÎNEMENT HYDRAULIQUE


    Contributors:
    JONES TONY (author) / BACON PETER (author)

    Publication date :

    2022-06-01


    Type of media :

    Patent


    Type of material :

    Electronic Resource


    Language :

    English


    Classification :

    IPC:    B64C AEROPLANES , Flugzeuge / F15B SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL , Druckmittelbetriebene Systeme allgemein



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