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REV: 04-29-25 LF <br />ENGINE FAN DRIVE <br />The engine cooling system fan shall incorporate a thermostatically controlled, Horton fully variable <br />type fan drive with SmartClutch J-1939 CAN controller. <br />The variable speed fan clutch only engages at the amount needed for proper cooling to facilitate <br />improved vehicle performance, cab heating in cold climates, and fuel economy. The fan clutch <br />design shall be fail-safe so that if the clutch drive fails the fan shall engage to prevent engine <br />overheating due to the fan clutch failure. The fan speed shall include a J-1939 CAN clutch <br />controller to receive signal from the engine control module to activate at variable rates of speed. <br />Variable speeds shall be set through thermostatic and engine speed signals to run as efficiently <br />and quietly as required to maintain temperature. <br />ENGINE COOLING SYSTEM <br />There shall be a heavy-duty aluminum cooling system designed to meet the demands of the <br />emergency response industry. The cooling system shall have the capacity to keep the engine <br />properly cooled under all conditions of road and pumping operations. The cooling system shall <br />be designed and tested to meet or exceed the requirements specified by the engine and <br />transmission manufacturer and all EPA requirements. The complete cooling system shall be <br />mounted to isolate the entire system from vibration or stress. The individual cores of the cooling <br />system shall be mounted in a manner to allow expansion and contraction at various rates without <br />inducing stress into the adjoining cores. <br />The cooling system shall be comprised of a charge air cooler to radiator serial flow package that <br />provides the maximum cooling capacity for the specified engine as well as serviceability. The <br />main components shall include a surge tank, a charge air cooler bolted to the front of the radiator, <br />recirculation shields, a shroud, a fan, and required tubing. <br />The radiator shall be a down-flow design constructed with aluminum cores, plastic end tanks, and <br />a steel frame. The radiator shall be equipped with a drain cock to drain the coolant for <br />serviceability. <br />The cooling system shall include a one piece injected molded polymer fan with a three (3) piece <br />fiberglass fan shroud. <br />The cooling system shall be equipped with a surge tank that is capable of removing entrained air <br />from the system. The surge tank shall be equipped with a low coolant probe and rearward oriented <br />sight glass to observe coolant in the system. A cold fill and observation line shall be included <br />within the frame mounted translucent recovery bottle to monitor the level of the coolant. The surge <br />tank shall have a dual seal cap that meets the engine manufacturer's pressure requirements and <br />allows for expansion and recovery of coolant into a separate integral expansion chamber. <br />All radiator tubes shall be formed from aluminized steel tubing. Recirculation shields shall be <br />installed where required to prevent heated air from reentering the cooling package and affecting <br />performance. <br />The charge air cooler shall be a cross-flow design constructed completely of aluminum with cast <br />tanks. All charge air cooler tubes shall be formed from aluminized steel tubing and installed with <br />silicone hump hoses and stainless steel “constant torque” style clamps meeting the engine <br />manufacturer's requirements. <br />ATTY/AGR.2025.089/Fire Apparatus Solutions (Purchase of Spartan-LTC 105' TDA) (Page 34 of 150)