ASCO’s Valves Used in Patented Braking System

Published: 28th November 2011 | Issue 19 Share article:

ASCO Numatics solenoid valve, pressure switch and nonreturn valve used in an innovative braking system for caravans and trailers

Modern trailers, caravans and horseboxes are designed to be stable and safe to tow, they feature a specially designed chassis with suspension and efficient brakes. Even so, as any experienced caravanner will tell you, a reduction in speed and change in driving style are essential when towing, and this applies particularly 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. This means there is a delay before the caravan brakes are applied. Now a new system is available that applies the caravan brakes as soon as the stop light circuit on the car is energised. Braking is quicker and more effective.

The new system is installed on the trailer and 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. This is used to direct air to the brake actuator when the towing vehicle’s brake circuit is energised and release the pressure when circuit is de-energised. An ASCO Numatics pressure switch 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.

Called Insync Brake Assist (IBA), the innovative braking system was developed by experienced caravanner Charles Irving and is now being manufactured and marketed by Insync Systems Ltd. “The sales and technical teams at ASCO Numatics have really helped to get the IBA into production,” said Charles Irving. “They provided excellent application advice and technical support and ASCO Numatics now supply a custom kit of parts with the pressure switch pre-set to our specification. This makes it easy to supply IBA kits to our team of installers located across the UK.”

The ASCO Numatics valve is ideally suited to this demanding application. It features a stainless steel core tube which provides exceptional resistance to humidity and corrosion. With a service life of up to 20 million cycles, the valve is designed for applications that require fast (5-10ms) and frequent operation. The valve being 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 1 million cycles, it can be adjusted over the range from 1 to 5 bar. The pressure switches supplied for the IBA are factory preset by ASCO Numatics.

“We worked closely with Charles Irving to ensure we provided the right valves and pressure switch for the job,” said Steve Barford, Senior Process Specialist, ASCO Numatics. “We know that many trailers and caravans are left unused for months and it was critical that the devices being used would respond immediately when required. ASCO valves have an outstanding reputation for quality and reliability and we are confident that our products will meet the challenges of this unusual application.”

The IBA consists of a small control box mounted inside the caravan. This houses the compressor, ASCO Numatics control valve, pressure switch and nonreturn valve. Electrical connections provide 12v power and inputs from the brake and reversing circuits. 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.

ASCO Numatics Ltd
Tel: 01695 713600
Website: www.asconumatics.co.uk

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