Pressure relief check valve arrangement for differential assembly

A pressure relief valve in a differential axle assembly comprising:

• a differential case adapted to be driven by an input shaft, said differential case containing a differential gear assembly to allow differential rotational speed between a pair of opposing output shafts;
• a pressure relief valve secured to said differential case and in communication with an interior of said differential case, said pressure relief valve comprising,
• a ball positioned on a valve seat formed on an external surface of said differential case, said valve seat being in fluid communication with a passage way leading to said interior of said differential case;
• a retainer disposed over said valve seat and secured to said differential case in a fixed position relative to said differential case, said retainer having an opening to establish fluid communication between said valve seat and an exterior of said differential case;
• and
• a spring disposed between said ball and said retainer, wherein, when fluid pressure in said passageway exceeds a predetermined value said ball is lifted from said valve seat to allow fluid to pass through said pressure relief valve to said exterior and when said fluid pressure in said passage way is below said predetermined value said spring maintains said ball against said valve seat to preclude fluid flow between said passageway and said exterior.

A pressure relief valve in a torque coupling device between an input and output shaft, said device comprising:

• a differential case in driving connection with said output shaft;
• a hydraulically actuated limited slip device disposed between said differential case and said input shaft to limit differential rotational speed between said input and output shafts;
• a pressure relief valve secured to said differential case and in communication with said hydraulically actuated limited slip device to relieve pressure in said limited slip device, said pressure relief valve comprising,
• a ball positioned on a valve seat formed on an external surface of said differential case, said valve seat being in fluid communication with a passage way leading to said limited slip device;
• a retainer disposed over said valve seat and secured to said differential case in a fixed position relative to said differential case, said retainer having an orifice to establish fluid communication between said valve seat and an exterior of said differential case;
• and
• a spring disposed between said ball and said retainer, wherein, when fluid pressure in said passageway exceeds a predetermined value said ball is lifted from said valve seat to allow fluid to pass through said pressure relief valve to said exterior and when said fluid pressure in said passage way is below said predetermined value said spring maintains said ball against said valve seat to preclude fluid flow between said passageway and said exterior, wherein said retainer has a raised portion spaced apart from said external surface of said differential case, and said raised portion has said orifice.