Anti Sink

Many great discounts and offered at Breakeryard, if you have any questions about any product you wish to purchase then please call our customer service today on *0905 232 3000 or e-mail us and we will contact you back promptly. What is a Anti Sink? Many contemporary vehicles have an anti-sink system (SC/ MAC) fitted, with the sole apparent purpose of tranquilizing the average driver by keeping the car from lowering when not used. The system does not interfere with the normal functioning while in use. It attempts to minimize leaks inside the system by hav-ing only one element that can leak, the antisink valve itself.

The layout is rather simple: there is an anti-sink valve fitted for each axle, between the height corrector and the suspension struts (or the hydraulic control block on Hydractive systems). The valves operate on the pressure differences in the system, without any electrical control: when there is significant pressure in their control circuit, they keep their work circuit constantly open (in fact, they are analogous to a simple electrical relay).

Under normal circumstances, the high pressure pump supplies the pressure regulator and the main accumulator with fluid. The output from these two feeds the whole system with high pressure, going through the security valve which keeps the brake circuit constantly under pressure, for obvious reasons of security. If there is enough pressure in the system, the security valve feeds the rest of the suspension via the anti-sink valves and the height correctors.

This pressure coming from the security valve appears in the control circuit of the anti-sink valves. When the car runs, the valves are constantly open, connecting the height correctors to the rest of the suspension and brake subsystems — everything functions exactly as in cars not equipped with this anti-sink system. Even when the engine is turned off, the valves remain open as long as the feed from the accumulator remains at a higher pressure than that of the suspension. But as soon as the leakage in the struts, height regulators and the brake valve reduces the pressure in the main accumulator below the suspension pressure, the closing anti-sink valves isolate the suspension struts from the rest of the system (see page 29 for a description of the Hydractive II control block). It is usually the front valve that closes first as the front of an unladen car is much heavier due to the engine and gearbox. Compared to a non-anti-sink car, the leakage is quite drastically reduced. For instance, a standard XM with its suspension in prime condition takes about 20-30 hours to sink completely, while with the anti-sink system this would take as much as ten days.

The rear anti-sink valve is connected slightly differently: in addition to feeding the rear suspension and the brake circuit, as usual, it connects to an additional anti-sink sphere as well. The function of this sphere is to maintain pressure in the braking circuit. As the brake valve is the most leaky element, it could exhaust the pressure between the piston and the plunger while the remaining pressure behind the piston (provided the high pressure and the front suspension circuits do not leak that much) stays rather high. In this case the anti-sink valve might open again in error— this additional sphere ensures that this will not happen.

The anti-sink system maintains the car height by counteracting the internal leakage of the various suspension element that would make the pressure escape back to the reservoir. Elements that are in constant motion— height correctors, for instance— leak past their seals on purpose to lubricate themselves; brake valves, on the other side, start to leak once they are worn. The anti-sink valves— which move very rarely, need no intensive lubrication, thus are manufactured with very close tolerances and hardly leak themselves— isolate all the struts from the rest of the system to prevent any possible leakage to reduce the pressure in the struts, allowing the car to sink.

Breakeryard are the Worlds Leading Supplier of Anti Sink car parts. We assure you a savings of up to 80%; we stock thousands of reconditioned, new and even used parts and give 100% warranties. You will not be beaten anywhere. We have great prices on our top-of-the-line products from our warehouses so get your brand new replacement Anti Sink without any sacrifices!