Diesel Engine Replacement Improves Pump Performance
Faced with an estimate of over $1,000 for overhauling an engine in a 750-gpm Seagrave pumper, the Columbus, Ohio, Fire Department turned to diesel power and wound up with a truck that met the standards for a 1,000-gpm pump.
When Assistant Chief D. H. Marshall looked at the estimate from the shop foreman, William H. Miller, he “felt the time was ripe for exploring diesel possibilities.” So he submitted a feasibility report to Safety Director Frederick J. Simon.
The engine selected was a GMC DH637, 4-cycle engine with 225 gross horsepower, a speed of 3050 rpm and 458 foot pounds of torque. The advantage of this engine’s speed, Marshall explained, was that it was comparable to the speed of the gasoline engine being replaced. Therefore, all the drive train components could be retained. Also, there was no need to change the pump transmission. An added bonus was the diesel’s weight, which was practically the same as that of the old gasoline motor. This eliminated steering, spring and brake problems.
After the diesel engine was installed, the pump underwent a sixhour test—at 150 psi for 3 hours, 200 psi for 2 hours and 250 psi for 1 hour. Gallonages pumped at these pressures were 1,008, 704 and 508, respectively. Spurt tests developed 1099 gpm at 150 psi, 750 gpm at 200 psi, and 740 gpm at 250 psi.
Marshall cited improved road performance as another advantage of the change. With the diesel engine, the pumper accelerated from 0 to 50 mph in 28 seconds and reached a top speed of 57 mph. Marshall also commented that very little gear shifting was necessary because of the high torque at low speeds.
The cost of the engine replacement was under $4,000, not including labor. Marshall explained that considerable labor would have been needed to repair the old engine and a realistic comparison of labor costs could not be made.
“Most important of all,” he commented, “we have increased the reliability of a piece of fire apparatus.”
The Columbus Fire Department was so well satisfied that pumper specifications were modified to provide for diesel engines in future apparatus. Plans also were made for phasing out gasoline engines over an eightyear period. Don Woodland, chairman of the City Council Safety Committee, indicated his indorsement of the replacement program.