Valve enables safe trailer braking
Published: 20 January 2012 - Rachel Morling
Although modern trailers, caravans and horseboxes are designed to be stable and safe to tow, a reduction in speed and change in driving style are still essential, especially when braking.
The normal caravan over-run braking system relies on the tow vehicle’s brakes and deceleration to compress the tow hitch and apply the caravan brakes, meaning a delay before the caravan brakes are applied. Now, however, a new system has been developed that applies the brakes as soon as the stop light circuit on the car is energised – ensuring quicker and more effective braking.
Installed on the trailer, Insync Brake Assist (IBA) uses pressurised air to operate an actuator that applies the trailer brakes using the existing rods and linkages. The air supply from the on-board compressor is controlled by an ASCO Numatics sub-miniature solenoid valve, which is used to direct air to the brake actuator when the towing vehicle’s brake circuit is energised and release the pressure when the circuit is de-energised. A pressure switch, also from the company, limits the maximum pressure in the system, preventing it from locking the caravan wheels. Pressure is maintained in the system using an ASCO Numatics non-return valve which prevents air being released back through to the compressor.
The valve features a stainless steel core tube which provides resistance to humidity and corrosion. The version used on the braking system is a 3/2 style with 12v DC operating coil. The pressure switch limits the pressure in the braking system. With an operational life of one million cycles, it can be adjusted over the range from one to five bar. The pressure switches supplied for the IBA are factory preset by ASCO Numatics.
The braking system was developed by experienced caravanner, Charles Irving, and is now being manufactured and marketed by Insync Systems. The IBA consists of a small control box mounted inside the caravan. This houses the compressor, control valve, pressure switch and non-return valve. Electrical connections provide 12v power and inputs from the brake and reversing circuits; and pneumatic pipes connect the control box to
the brake actuator assembly, which is clamped to the caravan chassis using specially fabricated brackets. The system is designed to fail safe in the event of a power failure, deactivating the IBA and allowing the over-run braking system to operate as normal.
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