The issue was taken to Design Engineer Ken Hare with motor mechanic and Quality Assurance Officer Kelvin Gleeson asked to find a solution.
“With this type of automatic transmission,” explains Kelvin, “the engine has to be above idle for the lockup clutch to engage when in pump mode. Once the lockup clutch is engaged and the transmission is dropped back to idle when in pump mode, firies found that the transmission or lockup clutch would disengage after one minute. This would lower the water pressure which is potentially very risky on the fireground, of course.”
Ken took the issue back to both Hino, the manufacturer of the cab chassis, and Varley specialised vehicles and asked how our trucks could keep the lockup of the torque converter engaged.
“Basically, Hino said we couldn’t do it,” continues Kelvin. “I understand they don’t like people doing modifications but we needed to make these vehicles work for our crews.
Kelvin spent two solid weeks working out the wiring. An electronic control unit (ECU) has multiple safety factors so it will go into failsafe mode if anything untoward happens within the circuit of the transmission.
“It was about trying to trick the ECU into thinking that it’s still driving down the road,” says Kelvin. “The lockup torque converter solenoid fitted within the transmission is controlled by a pulse-with-modulation signal. We had to find a pulse-with-modulation driver unit that could operate the solenoid.”
And he did!
“There are a lot of interlock signals within this transmission lockup control module or unit we’ve found, to only allow it to operate in pump mode,” continues Kelvin.
“On top of all this, though, was a second issue. The pump operator hadn’t been able to tell when the vehicle transmission was in lockup. We’ve now installed a red LED light in the rear pump panel and that’s sorted it out.”
The final part of the fix has been changing the throttle program when in pump mode with the base idle moved down from 1100 revs per minute to 900.
The complete fix was tested for one month on the new Skye brigade pumper and the feedback was all positive. Kenric Carter is both a Skye brigade lieutenant and a Cranbourne District Mechanical Officers so he was the ideal person to oversee the trial.
“In the first week or two we had a house fire and the pump got a solid workout there,” he says. “Because it was a new truck, we needed to train our operators at the same time. We took it to SETG [Southeast Training Ground] and pumped for about six hours straight and the fix worked as it should.”
DMOs Bradley Dart from Ballarat and Sean Botting from Seymour expect to work on some 68 vehicles by project’s end.
“We’ve split up the state between us,” explains Sean, “with me doing the eastern half. The job doesn’t actually need a lot of tools so we’re just taking the small utes out. We can do one truck in a day including getting to the stations so it’s not a huge job.
“We don’t need to give brigades any particular instructions once it’s installed; just a single sheet.”
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