I was using a D5H with powershift to push over a handful of 10-12" hardwood trees. I'm not overly familiar with how this transmission works. A few times when trying to push over a tree the machine would stop moving forward because it was out of power. The engine didn't stall so it seemed to be working ok, but when I would shift from 1F to 1R there would be a loud clunk, likely from quickly changing the flow of power. I don't think there were any loose or worn components it just felt like the transmission was under heavy load and then all of a sudden it wasn't. My question is whether this abrupt noise and jolt are normal with a powershift, or if this would be a sign of a transmission malfunction? If the machine was travelling forward and then you shifted to reverse, I wouldn't expect a loud transmission noise, so I was surprised when I heard this clunk after stalling against a tree.
Did you make a quick press of the decelerator pedal before/during the change of direction on the transmission control.? Did the clunk sound come from directly under your feet.? If it did it is possible for a universal joint on the driveshaft starting to give up the ghost.
Aarggg, Come on ... its powershift but it is still a dozer... Mechanichal one... so its necessary to unload the TXM by decelerating and wait TC to let go before any shifting either FWD-RWD or between gears. One can select strait from 1st FWD ro 2nd RWD, but use decel at all the times. Once u get aquainted to it its possible to FWD/RWD on the go, but it takes time to get it. Regarding power... well this babys are not new anymore but it should slip tracks in 1st gear against a rock or tree. Regards
I was using the decelerator pedal for all directional changes. I can't be for sure if it was directly below my feet, but I'll pay closer attention next time.
I definitely wasn't using full fuel rate so the tracks weren't slipping. But I will try to be more patient to see if the TC disengages. I thought I was waiting long enough at 2-3 seconds, but I'll try longer and see what happens.
Decelerator ! I think even the operators manual says it is not always necessary to decelerate. Me, depends on what I was doing if I used the decel pedal or not. I always kept the production going. If I was say maybe fighting a big stump most likely didn't decel. Oh yeah and is why I wish I could have my own machine I wouldn't have to put up with complaining about it. I remember many many whiplash direction changes in the day. Good neck muscles. Oh and I never damaged the machine that ran for years. Nothing worse than backing on a stump for back compression, and final drives, did not do that on purpose but things happen when clearing in conditions in this state. I think there are some old cat ad's on youtube that tout the powershift as something for quick direction changes over what the old manual transmission and clutch could not do.
My Cat operators manual says something along the lines, The transmission is designed for full speed direction changes but decelerating can give longer life of components. If you have a foot decelerator it should be second nature.
Come on Gents... Its how it is... the system can´t be changed... and i dont think CAT was thinking about fighting stumps when they wrote the user manual. A series H powershift TXM shifts crude in less than a second at FTH, got no damping, when the machine is against a wall and one neutral´s gears , it just shocks TXM(sprockets and tracks) as they go from full TQ to neutral, using both decel unloads the TC and the shock is minimal. Later models have damping systems and HYD power compensators... basically an electronic module help the operator in those tasks. For instance a D6D power shift is much smother than a D6H...dif tec
The older power shifts, I think there is a modulator valving to allow for the full throttle direction changes. And besides the torque converter is an inline cushion as well. I would bet those old cat skinners, say on the alcan project (direct drive,clutched) shocked components more on direction changes than any non decel power shift ever does. Oh by the way a clunk going forward and reverse, can also be a sign of a loose transmission to bevel case.
I got to know D5H powershift TXM/TC systems better than i wanted. And i got astonished for the lack of any kind of modulating between TC and TXM valves. Other thing that lifted my eybrow was lack of standby hydraulic flow for operation in low idle, there´s no HYD acumulator in the system... As far as i have used a DD TXM with main clutch one can avoid all shock just by learning to use clutch... Same is for H series powershifts, requires learning and skill to avoid shock of components. Some H models were offered with diff steering, and this is a very good solution, as this system have some complicated modulation that from driver point of view is very nice, from owners perspective i´m not sure if it is a good system. Anyway strange noises can come from several components , better to do a good turnaround to find something loose.