Tamper-resistant brake actuator

In a fluid-operated brake actuator of the type having a generally cylindrical head with a first annular flange, said first annular flange having a radially outwardly protruding shoulder and an annular rim extending axially from the shoulder, said rim having an inward face and a terminal annular edge, said actuator further having a flange case with a second annular flange, said second annular flange having an axially disposed outward face in confronting relationship to the inward face, said head and flange case thereby defining a chamber, and a power spring compressed within the chamber, the force of said power spring tending to separate the head from the flange case, the improvement comprising:

• a first annular groove in the inward face, said first annular groove being disposed axially from the terminal annular edge,
• an opposing second annular groove in the outward face, a portion of the outward face being in confronting relationship to the inward face between the first annular groove and the terminal annular edge, and
• a ring having a radial outward portion disposed in the first annular groove and a radial inward portion disposed in the second annular groove,
• whereby the head is securely fixed to the flange case and the ring is substantially inaccessible from the exterior of the brake actuator thereby deterring manual separation of the head from the flange case.