Safety device for grinding heads

Claim 1

IN A GRINDING HEAD CARRIED BY A SLEEVE-SUPPORTED MACHINE SPINDLE, THE HEAD HAVING A FLUID PRESSURE OPERATED MOTOR AND NORMALLY ROTATING AND NORMALLY NON-ROTATING MEMBERS, INCLUDING AT LEAST ONE ELEMENT ROTATABLE COAXIALLY WITH THE SPINDLE AND A NON-ROTATING SLIP RING CARRIED BY AND INDEPENDENTLY ROTATABLE WITH RESPECT TO THE COAXIALLY ROTATABLE ELEMENT, THE SLIP RING HAVING A FLUID INLET AND FORMING WITH THE COAXIALLY ROTATABLE ELEMENT AN ANNULAR FLUID PRESSURE CHAMBER IN CONTINUOUS FLUID PRESSURE COMMUNICATION WITH THE INLET AND THE MOTOR; A SAFETY DEVICE FOR RESTRAINING THE NON-ROTATING HEAD MEMBERS FROM ROTATION AND FOR SUPPLYING FLUID UNDER PRESSURE TO THE SLIP RING, COMPRISING: A TORQUE RING SECURED TO THE MACHINE SPINDLE SLEEVE, A SHEARABLE PIN FIXED IN THE TORQUE RING AND PROJECTING DOWN ALONGSIDE THE HEAD, A TORQUE ARM PROJECTING RADIALLY FROM THE HEAD AND ENGAGED WITH THE SHEARABLE PIN, THE TORQUE ARM BEING FIXED TO A NORMALLY NON-ROTATING MEMBER, A SUPPLY CONDUIT CONNECTED TO A SOURCE OF FLUID UNDER PRESSURE AND HAVING ITS DISCHARGED END SECURED TO THE TORQUE RING, AND A FRANGIBLE HOSE FLUID CONDUCTIVELY CONNECTED AT ONE END TO THE CONDUIT DISCHARGE END AND AT THE OTHER END TO THE SLIP RING FLUID INLET.