Some issues are starting to show up at the Southwest Engine Academy on the Type 3 Engines. We chose the latest generations of the USFS national standards to put into the pumping practical portion of the academy. These models are the Model 346, BME built and have the Freightliner chassis. While pumping these engines for the last ten days, we are starting to see a “high idle” mode the truck puts itself into. This mode affects the pump side of the truck as well. Once the high idle mode starts itself, the pump side of the truck generates approximately 90 extra PSI while the pump is engaged. So for instance, if a student is pumping during their practical and the engine goes into high idle, the PDP the student has set on the pressure gauge is off by the 90 PSI the high idle creates. So, if the pump is set at 150 PSI, and the high idle kicks in, we now see 240 PSI on the pressure gauge and that pressure is sent to the nozzle at the end of the hoselay. We have been testing two of these trucks for the last ten days. One truck will allow the pump operator to engage the PTO at high idle. The other one will not allow the PTO to engage during high idle.
This unforeseen rise in pressure of approximately 90 PSI poses a serious risk to the operator and nozzle person. The other risk is the inability to engage the PTO for water deliver. |