I suspect on the whole they were reliable gearboxes - provided maintenance was carried out correctly.

@@millomweb They were more reliable with air actuation compared with the hydracyclic version. But no gearbox would withstand repeated abuse from a driver who just rammed through the gears,... unfortunately plenty did. These training videos were meant to inform drivers about the engineering so they would be more respectful of the vehicle and its systems. The videos proved more effective than the Chief Engineer shouting and balling at the drivers for "wrecking" his fleet!

@@Neash2 I suspect the worst would be changing up a gear while accelerator still flat to the boards ! Currently, my favorite is the variable pulleys fitted to the Invacar. kzfaq.info/get/bejne/oJiantx0xsfWlGQ.html This ticks all my boxes - 2 entirely mechanical analogue 'computers' playing tug o' war with a belt. Their weakness is power handling (torque) - so, my solution on the bus......I hope you like this !!!!!! is to drive 4 of them with the engine and each one driving 1 back wheel - so yes, the inner back wheels would be on their own solid drive shafts and the out back wheels driven by a drive tubes ! 4 wheels with independent drives would mean no need for diffs ! The four 'gear boxes' would balance out the power/torque to each wheel - and if a belt failed, the other 3 wheels would still provide drive. You'd have 4WD on 1 'axle' !

Was the thumbs up for the pedal to the boards part ?

You are very welcome, I'm pleased the video was helpful.

You seem to have a stutter there. I guess you mean DMU. There is or was a video on YT about driving the DMUs - about the only thing I remember was to only coast in top. Although there was quite a bit of emphasis on giving the engine a long time to decelerate before changing up :) Depending on your response, I might have to explain British Stamps :) And now my mind is on a new train mechanical transmission :) (I was going to say we don't have electric round here - even the signals have oil lamps in them - but that's a jokey lie :) (Signals isn't a jokey lie though not traffic lights, semaphore signals ! (Actually, I prefer them - as they can be read from both sides :) )

@@millomweb DMMU - Diesel Mechanical Multiple Units. The were Diesel Hydraulic and Diesel Electric Multiple Units too, but only the Mechanicals had the Wilson Epicyclic 'box. You are absolutely right, only coast in top gear (4th). Too gear was a ditect drive that locked all the gear trains together. We didn't have the luxury of 'Overdrive' - so a maximum speed of 75mph! Ah - they are proper signals then! Only proper signals have an oil lamp (or glow worm as my instructor used to call them!) He did have a stutter, and used to drum into us the importance of changing up and down properly (close throttle, count to 4, change gear, count to 4 again). 'Otherwise you'll burn out the f f f ' and we always thought he was going to say 'f@#ing thing' but it was always 'f f f fluid-flywheels'. I can't think of fluid-flywheels without the preceding f f f now. Funny how things stay with you. I can remember what the speed range was for each gear (1st : 0-15, 2nd : 15-27, 3rd 27-41 and 4th : 41-75) But i can't remember my bank PIN!

@@TheZacDJ Why not make your bank PIN 'top gear': 4175 ! I knew I was going to have to explain British stamps........... They're the only postage stamps in the world that don't have the country of origin on. WE WERE FIRST ! Similarly, ALL DMUs are mechanical. They're called DMUs ........ DEMUs are eectrical and DHMUs are hydraulic. As soon as you say DMU you know that only half the carriage light bulbs are visible :) as they stick half the bulb below the shroud ! The signals are actually electrically lit. The battery boxes at trackside are part of the clue. But yes still semaphore on the entire Cumbrian coastline. Worth a trip on it just for the sake of it. A fair bit of it - one side you see land, the other just sea water - if the tide's in. Then there's Bransty tunnel. That limits the length of the carriages ! What's more, it was totally unnecessary to dig that tunnel but mr flatland land owner refused to let the railway on his land ! Now for the bad news. Your stuttering tutor was wrong ! Yeah you could cook a fluid flywheel but on a frosty morning, setting off in 4th would quickly warm it up :) The fluid flywheel actually takes all the battering any reasonably bad driver can give it. The 4 second pauses are to minimise brake band wear on ratio selectors. The first 4 is so the engines aren't running faster than they'd be pulling in the new gear and the second four is to give the newly selected band to get fully tightened before putting the power on again - so it doesn't slip. I actually once abused a farm tractor on this very point. It had a 2 speed lever on it as well as a standard 4 speed box (no synchromesh at all) and I used the 2 speed lever to select the faster speed while going too slowly - the engine wasn't running fast enough to provide proper hydraulic pressure on the band - and it caused it to slip for a bit ! At least after that, the 2 speed change was less jerky :) I can remember my Dad's bank PIN - yes, from THAT railway loco !

First generation British rail diesel multiple units were buses on wheels

Hi I'm deano from skelmersdale Did you ever get a reply or find out why your 4 gear locks ? Did you talk with other bus specialists

..I'm guessing you're fixed it, plenty of Leyland clubs for advice

These only have two elements from my understanding, while a torque converter has a third. These only give a linear transfer of torque while a torque converter will give torque multiplication under stall ...or something like that anyway.

I'm guessing Mid 70's

followed by London Road, Preston!

I'd agree it looks complicated but to be honest, it's not - on the basis that there are far more complex things and there are better designed things - in fact, 'same' gearboxes but foot pedal operated rather than air operated. It wasn't mentioed whether this was a pre-selector gearbox. Basically, you have a contol lever for the driver to select a switch to turn on. That uses electricity to open an air valve and then the power of compressed air does all the actual work. The film covers maintenance procedures - on what appears to be a fairly well designed system which includes automatic adjustment of wear items. If maintenance is done properly, it should be reliable.

They were used by European bus manufacturers such as Volvo, Scania, Saviem, later Renault as well and were a player alongside ZF, Voith, Allison in the citybus gearbox market there. They were good if driven sympathetically.

@@jamesfrench7299 'sympathetically' - yes, lol - it's a pity they don't operate with sympathy for the driver ;) Going down a hill once in an auto car I wanted some acceleration - so anticipated a down-change - so I pressed the accelerator a bit further than I normally would. I didn't get the down-change just far more acceleration than intended !

@@millomweb my 89 Automatic Mazda 323 with Jatco 4 speed automatic with overdrive lockout button on the shifter has excellent engine braking effect as autos go. Nothing beats a manual for saving brakes though, except a Telma retarder or regenerative braking in a Toyota Hybrid.

@@jamesfrench7299 Engine braking on my bro's Audi manual is just about absent - to the extent I even turned the ignition off to see if the engine management system was still injecting fuel. Didn't make any difference ! What wears brakes out on our vehicles is rust - on the discs !

Not the most efficient but very tough.