What I want to know is this during the preview stream just trains stated they were adding the missing hold gear switch to the pacer when can this be expected as this is missing from update patch notes
I imagine adding a hold gear switch would probably require some physics adjustments for it to work so i’d give it couple more weeks
So it'll be the round black button, where the "Windscreen Wash" is placed on JT's model (and many Pacers irl). Which ones were fitted with the gear hold button?
It’s on the panel where the compressor switch and engine on off is for example if you look at ap pacer pack on YouTube you’ll see where it should be
It was intended to be on the just trains one I asked them directly in there just trains pacer preview stream and I quote “We are aware of this however this occurred later in development process therefore it was too later to get this in final build in time for release we are looking to get this added”
I think it was actually retained into the TL11 and Voith transmission days as otherwise if you had a mixed set which did occur and were driving from the voith fitted one you would be unable to hold the gear on the SCG fitted one. I suspect once all the SCG boxes had been erradicated then there were removed, so I suspect they were probably removed when they went into for the engine change to cummins. Other BR units that worked in multiple with the Pacer als also had a hold gear switch for similar reasons, such as the class 150 as show here on row C http://locodocs.co.uk/brmanuals/150-1--150-2GeneralInfoDrivingInstructions-1987/photo22.jpg
I'm having trouble figuring out what the "gear hold" button would actually do, since the documents that would explain that in detail are missing from "locodocs". Does it simply modify the speed/RPM thresholds for gear changes in some way?
In theory it should prevent a upshift/downshift when on a steep gradient where the loco/dmu cannot keep the necessary speed up. When going uphill it should prevent stalling or absolutely trashing the fluid converter in the low rpm range. When going downhill it can act as a retarder to keep the speed of the train in check. In both cases a very useful button to have Cheers
It doesn't prevent a downshift, and its impossible to act as a retarder anyway in this gearbox arrangement as there is a freewheel in the driveline. To quote the drivers manual for the 142:
Ah yes, that's precisely what I was looking for. If only that particular manual was on locodocs… So basically, the gear-hold feature is not terribly useful on the Blackpool route, as none of the gradients are so steep as to prevent accelerating in 4th gear (assuming both engines are working) - or if there are any, they're too short to matter. Even when hauling a second dead Pacer in one of the scenarios, I didn't see any problems with gear hunting. There are other routes where a Pacer might conceivably be deployed, however, that would have noticeably steeper gradients; of the routes in TSW, the obvious candidates would be West Somerset (the Devon Banks are notorious) and Northern Trans-Pennine (Miles Platting Bank in particular). In the 101, it's a matter of driver's judgement as to whether a gear change is warranted, but the Pacer's automatic gearbox has a relatively dumb logic behind it. It's not possible, for example, to pre-select a higher gear while coasting at a speed just below the change point, in anticipation of clearing a speed restriction. So you open the throttle, the engine revs to maximum, then almost immediately cuts out again for the gear change. You would almost prefer to have the semi-automatic gearbox normally fitted to buses…
Pages 14-15 of the above manual detail an additional use of the Gear Hold feature, ie. bypassing a protection system when starting away on a particularly steep gradient, especially with one or more engines shut down. The gearbox logic apparently assumes that if you've been at full throttle for at least 20 seconds, you should be going at least 10mph by then, and if it doesn't sense that having happened, it assumes there must be a fault. One such potential fault would be in the speed sensor, so it selects 4th gear to avoid over-revving the gearbox components (the freewheel and fluid coupling both being on the engine side of it).
For those who perefere realistic procedures here the other parts of the manual (there is also a 142/1 issue 2 with diagrams, but didnt make the scan by now:
