D7e decelerator and powershift questions

You can't go wrong by bringing the machine to a stop during direction changes, I always did on my D8's. You can shift from forward to reverse in one motion, there is no need to shift to neutral before stopping. Say you are traveling forward and want to back up you would decelerate touch the brake to stop and at the same time shift from forward across neutral and into reverse and off decelerator, back you go. If the machine is slightly moving it won't hurt anything but I have seen teeth broken off the ring gear form shifting from F to R without stopping. Upshifting can be done without decelerating just shift it under power, downshifting can be done also without decelerating if the machine slows to the lower gears travel speed. Say you are pushing in 2nd when the machine pulls down to the approx. 1st gear travel speed you can slip it into 1st under power without decelerating. These shifts will happen smoothly, if you get a distinct clunk or jerk in the machine your timing of the shift is off. I would not shift from full speed 2nd to 1st without decelerating again you match the machines speed to the lower gear so if you are running unloaded in 2nd and want to downshift you would decelerate to the approx. 1st gear travel speed then shift. You will get used to the torque converter and practice makes perfect. If it is smooth you are good. Always put it in N for parking and get into the habit of using the safety lever when you get off so the shifter can't be accidently move into gear when getting on or off the machine. Stay out of 3rd completely unless there is a fire or some equal emergency, your undercarriage will thank you for not using it. Hope this helps

In the original literature associated with the "new D7E" and the powershift transmission, Cat stated that the Cat powershift transmission was quite capable of directional shifts at full load RPM, without deceleration.
Constant deceleration and then acceleration to change direction increases fuel useage, and Cat claimed their powershift transmission was superior in this ability to change direction without deceleration.

However ... the early powershift transmissions as fitted to the 48A D7 engaged the clutch packs rapidly, with no clutch oil pressure drop, resulting in fairly harsh shifts, both in directional and speed changes.
After a few years (around the early 1970's), Cat engineers decided that a modulating valve that dropped the clutch pressures for a second or two, when changing direction and speed, would be a good idea to reduce transmission shifting harshness and to prolong drivetrain component life.

Accordingly, from around 1972 or early 1973, Cat powershift transmissions gained a modulating valve in the valve body mounted on top of the transmission.
The modulating valve drops the clutch pack oil pressure temporarily when a directional or speed change was initiated, and then raises it again to full operating pressure within a second or two, to engage the clutch packs more slowly.
This has the effect of providing a very smooth "soft-shift", and this modification eliminated the harshness of the directional and speed changes of the earlier Cat powershift transmissions.

Accordingly, as your 48A transmission is an early model, decelerating a certain amount as you change direction is advisable to prolong transmission and drivetrain life.

It's like anything OZ, the easier you are on it the longer it will last, what the machine will do and what's best for you may be two entirely different things particularly in a machines twilight years where cycle times really don't matter.

Thanks for the advice DPete and OzDozer,i am trying to be easy on the old dozer as i can't afford costly repairs.Just back to one of my questions,so can the dozer be held in gear at idle without moving for some time or would this overheat the transmission.

Probably won't heat up at idle but I would always put it in N and throttle down to give my right foot a break if it was any length of time, can't think of any reason to sit in gear for a long period.

There's no problem with holding the tractor in gear at idle for some time - the transmission drivetrain contains a torque converter that allows for "stall" - whereby this enables the engine to run, while the output shaft is stopped, same any standard vehicle automatic transmission.

But as DPete says, there's normally no reason to hold the tractor in gear at idle for an extended period - unless you're holding pressure against something with the blade.

The cooling system is capable of removing the heat generated at stall, while the engine is idling - however, if full throttle is applied, and the torque converter is kept at stall, transmission oil overheating will happen rapidly.
You will see this rapid oil temperature increase virtually immediately on the transmission oil temperature gauge, if this situation occurs.

Naturally, any event that sends the transmission oil temperature into the red zone will harden the o-ring seals and gaskets, as well as hardening any rubberised hoses in the oil lube system.

I took the dozer for a drive today and have adjusted the decelerator idling so the revs are low enough so as not moving forward in gear and only my foot lightly on the brake, as before the adjustment i would have to hold the brake down hard to stop it from wanting to move forward.I pushed a fair bit of dirt today with no problems,and seems to keep cool even on a warm day.I wasn't sure whether the powershift transmission was the same principle as a car automatic so thanks for letting me know ,as in the past with the decelerator not working properly it would try to move as soon as it was put in gear and always looking for neutral to stop it even at lower revs,so i always the decelerator now working is definitley good to have.Thanks for the information,
cheers John.