Leyland Bus Training Film: Self Changing Gears SCG Semi-Auto Pneumocyclic Wilson Gearbox Maintenance
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- Опубликовано: 28 дек 2020
- Leyland Bus Training Video
Self-Changing Gears (SCG) / Wilson Pneumocyclic Gearbox
Semi-Automatic with Electro-Pneumatic Control
Maintenance, Control Systems, Adjustment and Fault Finding.
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Brings back memories of my days working on Leopards in the North East - thank you for uploading!
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.
ruclips.net/video/j2jkyCaard0/видео.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 ?
A video is far better than the Leyland manual which would have explained a lot more about auto adjustment. Brings back so many memories of fluid flywheel repairs and oil pump gear repair and pressure testing. Remember using that measuring tool primative but did the job. Don't know if it was approved but our company put dump valves on ours to quicken the release of the band but also caused so many breakdowns for sticking or bursting the diagfriagm... Nice sound though going through the box
This video just helped me! Not to disassemble my gearbox again. Very big thanks for uploading this video. I myself have a Swiss Saurer SLK 525-23 bus, with a Leyland GB 349 (identical to GB 342).
You are very welcome, I'm pleased the video was helpful.
Thank you for bringing us this excellent and informative video, it is much appreciated by the people.
60s~late 80s Hong Kong double deck buses used to be equipped with these gear sticks/semi-auto gear box
Mecánica a la vieja escuela. Y el sistema neumático muy interesante
Excellent viewing, thanks for uploading!
We had the same self adjustment mechanism on the SCG boxes used on British Rail DMMU Trains. The joys of Epicyclic Gearboxes and f f f fluid-flywheels!
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
Brilliant video. Very informative. Especially the brake band adjustment. I feel most bus companies don’t follow this procedure to the letter and their drivers are definitely not trained how to change gear properly. 😬
I like how we are given the sequence in which you’ll destroy the gearbox’s clutch plates if you tow it.
Very interesting
The Ford model T used the same transmission design. Their bands were controlled by pedals.
"Axle shaft" - I thought that was a daft Americanism for a half-shaft ! First time I've seen it used in the UK.
Hello from New Zealand. What does the intermediate connection as seen at 8.50 actually do please. Thanks
Shame Leyland couldn't build there cars with this sort of detail
This is soooo cool.. i have a bus with a gearbox that looks like this (but only 4 forward and 1 R), i have just adjusted the gearbox to get 2 gear working, selfsdjusting didn't work... but would like to know the correct distance, don't have the special tool :-), but i stille have an issue... 4'th gear is not engaged.. but insted it just "locks" the shaft. now where to find information about this ?
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
PLEASE HELP! ANYONE IN THE KNOW OUT THERE! I have Leyland Atlantean 1971 here in Australia. Had gearbox failure completely rebuilt it using genuine new parts. After reassembly we got stuck in 3rd gear and can't undo it no.matter what we do. How to fix this please? Thanks!
..I'm guessing you're fixed it, plenty of Leyland clubs for advice
When does this video date from?
I'm guessing Mid 70's
Is what they're calling a flywheel actually more like a torque converter?
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.
Derby bus station
followed by London Road, Preston!
That looks so over complicated. was it reliable ?
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 !
Thank god for Allison Transmissions haha
Not the most efficient but very tough.