1. Field of the Invention
This invention relates to a vibration damping device for use on an axle of a railway truck.
2. Description of the Prior Art
Vibration dampers used to prevent sporadic oscillations or "hunting" of an axle of railway trucks are old and well known. Such dampers have generally been of the hydraulic type in which a piston having valving reciprocates within a fluid filled cylinder. The cylinder is generally connected to the car body of the railway car and the piston is connected to the axle housing.
The axle housing, in which an end of the axle is journaled for rotation, is generally engaged with and supports a resilient suspension member, such as a leaf spring, which resiliently supports the car body of the railway car, as well as any cargo with which the car body is laden.
Due to the resiliency of the spring, the axle and the wheels mounted on it tend to, under some conditions, "hunt" at high speeds or make sporadic jerky movements as the truck is forced to accomodtae frequently occuring track curves or rough sections of track. Such movements tend to require a rough, energy inefficient pulling of the car and may, under extreme conditions, cause derailment. Vibration dampers have been used to smooth out or damp such oscillations. These commercially available prior art dampers are of the hydraulic piston and cylinder type having hydraulic flow control valves and relatively complex and expensive seals.
Due to the conditions of stress and temperature extremes in which they are forced to operate, the durability of currently commercially available hydraulic type vibration dampers leave much to be desired. Leakage of fluids and stickikng or wear of valves often cause them to be relatively ineffective and require the need for frequent maintenance, repair or replacement.