Thermal Rig Puts Brake Systems to the Test

AP Braking, a division of AP Hydraulics Ltd, has expanded and upgraded its R and D facilities with the installation of a specially modified Carbolite thermal chamber suitable for long-term test programmes involving flammable liquids.

The new equipment is an upgraded version of an existing chamber used by the company for several years and is designed to accept rigs for thermal stroking tests on components such as brake cylinders and calipers. These components can incorporate a number of different metals and plastics, as well as various fluids and greases.

Thermal stroking tests are carried out by attaching components to jigs fixed inside the chambers, with hydraulic pipework passing through the oven walls to external actuators. Up to four components can be tested at a time. A typical SAE (Society of Automotive Engineers) test requires brake cylinders to be subjected to 1000 strokes per hour for 70 hours at a temperature of 120°C to simulate conditions in an engine compartment.

The chamber has a maximum temperature of 200°C and can be programmed to provide temperature cycling if required. It is integrated with the test rigs, so it automatically switches off if a fault develops, and an explosion relief panel is also fitted.

In case a component fails, surfaces that could come into contact with flammable liquids are below their auto-ignition temperature, and elements are positioned away from flammable vapours. The chambers are also sealed to prevent liquid escaping. Internal lighting has been fitted so that staff can see clearly when setting up equipment.