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(last edited July 20, 2005) Front Page | Recent Changes | Title Index | User Preferences | Random Page | HelpAlso known as a Retainer. A valve used to vary brake application individually on each vehicle depending on the weight of the vehicle, it can be manually or automatically operated. In the manual version - used on freight vehicles only - a lever at the side of the wagon must be set for the required position.
Automatic versions of variable load valves are now often used. A simple version is operated by a lever connected between the valve mounted on the car underframe and the bogie frame. As the car load increases, the lever detects the depression of the car body and valve relative to the bogie and adjusts the setting of the valve in direct proportion.
On vehicles with air suspension, the lever is used to adjust a levelling valve which changes the air pressure in the suspension system so that the car body maintains a constant height, regardless of the load. Changes in the suspension air pressure are detected by a separate variable load valve and the brake application adjusted to suit.
The variable load system can also be used to adjust train acceleration so that it is constant regardless of load.
