By now, we are all very familiar with many benefits that come virtually free when using a hydraulic fan cooling system — managed engine loading, lower fuel consumption, less fan noise, lower maintenance costs and fewer trips to the repair depot — the value proposition list goes on and the ROI is a dead certainty, not to mention the feel good factor of an environmental plus with every installation.
About five years ago, Central Ohio Transit Authority’s (COTA) vehicle maintenance department at McKinley Avenue, Columbus, had overheating system issues on an in-service rear-engined passenger bus caused by the underperforming cooling system. Michael Suchecki, the heavy repair supervisor, called Ed Spahr from Sunsource Hydraulic Service & Repair in Hillard, Ohio, and together they began investigating the problem.
It was determined that even with a standard pressure wash down schedule in place, the side-mounted radiator was getting clogged with road debris and loose dirt, enough of which was sticking to the core, reducing the elements efficiency and useful cooling area. Spahr recognized the symptoms and knew the solution that was needed was an upgrade to a reversible hydraulic fan drive.
Looking at the system, the hydraulic pump configuration was fine, but the existing fan motor would need to be changed to a bi-rotationalversion and an external manifold block with speed control (variable pressure) and directional (fan rotation change) valves would need to be added. The fan reverse sequence needed to be technically addressed, so High Country Tek Inc. was contracted and recommended its standard HFS-2 controller. This model was chosen because of the retro-fit simplicity, and also because it is completely sealed in flame-resistant resin ensuring reliable operation under the extreme conditions seen by a road vehicle that can be working seven days a week.
This particular module also provided a way to safely sequence and simply program the fan reverse or purge feature to clear the radiator at pre-set regular intervals.
Questions regarding safety of passengers and people or property in the vicinity of the radiator during a cleaning cycle were raised, with the automatic assumption being that the fan would rotate at the same high speed in reverse as when in normal operation. The biggest concern was debris ejected at high speed.
These concerns were fully addressed before work started by ensuring that the cleaning cycle would be triggered several times a day, reducing the opportunity for debris buildup, with the fan speed limited to as fast as was necessary to dislodge the majority of the blocking material in a safe manner, while ensuring that it would fall behind the radiator protective grille and safely onto the road surface.
With the HFS-2 controller, the fan reverse feature can be set to fully automatic. In this mode, operation is transparent to the bus driver and customizable settings allow reverse interval, reverse time and importantly, fan reverse speed to be individulally set and tailored to suit any safety need, fan blade type or manufacturer’s recommendations. A soft-shift directional valve was also used to further minimize any system shocks or operational noise during the fan reverse cycle.
The result of the system improvement was a very clean radiator as seen below, a bus engine working at optimal temperatures meaning higher fuel efficiency and a reliable cooling system that is still running every day in and around Columbus, Ohio.
The maintenance department of COTA has now had five plus fault-free years of operation from the upgraded bus cooling system, with the savings made, returning the upgrade investment very quickly and also extending the vehicle useful life, making better use of available capital budget, while satisfying customer service needs and complying with the latest EPA emissions regualation.