Background In a traditional fan drive the fan is linked to the engine through a belt drive or mounted to the crank shaft. This means that the fan will run at a speed determined by the engine and not determined by the required cooling power. In an electric on/off installation it will either run at full speed when above the cut-in temperature limit or stall when below the cut-off temperature. These systems will cool the engine in quite a wide temperature range, in some cases even ”more than needed” at the cost of fuel, noise, energy and emission. ”The Haldex design” In the Haldex Hydraulics fan drive, the fan speed is controlled independently from engine speed and will only run to supply the cooling power exactly as required – not less and not more and independent of the engine speed. Fail safe It has an integrated failsafe feature. If a failure occurs in the electric system, cables, sensors or control unit, the fan speed is automatically adjusted to maximum cooling power and prevents the engine from overheating and costly engine damage. Times are gone with engine breakdowns caused by a defective fan belt. Flexible This hydraulic fan drive system enables design flexibility since units can be located remote from the engine. Additionally this means the radiator airflow can be optimized with regard to minimum noise emission. Correct speed A smooth ramping up and down of fan speed by a proportional pressure control avoids mechanical shock loads compared to systems with simple on/ off coupling systems. Temperature Engine cooling temperature and hydraul ic fluid temperature are presisely controlled within a narrower temperature range compared to other systems. The fan speed is essential on the machine for emission, noise and fuel consumption. Example: A fan running at 1000 rpm and 2 kW power input, will need 8 kW to run at 2000 rpm. So by making the fan independent from the engine speed the fan will run only at required speed and consequently consume just the power needed. The proportional pressure relief valve controls the torque of the fan and generates the most precise speed control. Optional: Electronic Control Unit is available directly mounted to the solenoid valve. It has 3 input signals, 2 of them are analogue, for cooling of e.g.. engine, hydraulic circuit or transmission, 1 is a digital signal e.g. for air-condition or retarder. This Electronic Control Unit has just the size of a matchbox. Connectors of the outgoing cable can be provided to suit customer wire harness demand. Adjustment of electronics, solenoid and sensors is factory preset. Complete solution Haldex Hydraulics supply complete systems including hydraulic pump, hydraulic motor with pressure control and the Electronic Control Unit with temperature sensors. Other features like AC-valve, reversible fan direction, pressure gauges etc. are optional. All motors are equipped with a shaft seal designed for high back pressure and pressure spikes in the return line. This eliminates the need for a case drain line of uni-rotat ional motors in many applications. Bi-rotational motors are available as well. The system offers the capability of being integrated into existing hydraulic and electronic systems of the machines. quality products for mechanical & fluid power ~ jbj Techniques Limited, www.jbj.co.uk UK distributor for Concentric Hydraulics
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