Special key to enable high gear

[notadriver]

Does anyone know which bus types had this feature to enable high speed running ? Why was this feature discontinued - it doesn’t seem present on modern buses.

 

[CN04NRJ]

Cardiff's dual purpose seated Mk1 Leyland Lynxes (F237-240CNY) had the key to enable 5th gear (ZF), it was only given to private hire drivers. Way before my time there but I was told it was to limit speed and fuel consumption on city work - allegedly they were good for over 70mph.

 

[Geordie driver]

Cardiff's dual purpose seated Mk1 Leyland Lynxes (F237-240CNY) had the key to enable 5th gear (ZF), it was only given to private hire drivers. Way before my time there but I was told it was to limit speed and fuel consumption on city work - allegedly they were good for over 70mph.

We had Volvo Olympians that would do 80, checked by the police. Don't ask how I know!

 

[TheGrandWazoo]

I seem to recall that certain grant spec Leyland Leopards had some sort of switch on the gear lever to allow a change from low to high speed diff? I was young and I'm no engineer, so might be bunkum.

 

[mainframe444]

I seem to recall that certain grant spec Leyland Leopards had some sort of switch on the gear lever to allow a change from low to high speed diff? I was young and I'm no engineer, so might be bunkum.

Your memory does not fail you, I worked for United Counties in the 80s and most of their Leopards had twin speed rear axles, there was a flick switch attached to the air change lever.

The best of these were the ECW B51 bodied ones, very light body with a two speed axle made for very lively performance.

I had one on a Nat Ex duplicate one day, the service coach driver with his Volvo was most impressed that I could easily keep up with him!

M

 

[TheGrandWazoo]

Your memory does not fail you, I worked for United Counties in the 80s and most of their Leopards had twin speed rear axles, there was a flick switch attached to the air change lever.

The best of these were the ECW B51 bodied ones, very light body with a two speed axle made for very lively performance.

I had one on a Nat Ex duplicate one day, the service coach driver with his Volvo was most impressed that I could easily keep up with him!

M

Thank goodness for that.

The vehicle in question was slightly older, and was a Duple bodied of United Auto. I suspect it was a diverted order in the late 1970s and I don't think it was perpetuated on their later Leopards. Something about damage caused by flicking from low to high ratio at speed?

 

[mainframe444]

Thank goodness for that.

The vehicle in question was slightly older, and was a Duple bodied of United Auto. I suspect it was a diverted order in the late 1970s and I don't think it was perpetuated on their later Leopards. Something about damage caused by flicking from low to high ratio at speed?

There was a knack to it, from low to high you flicked the lever, took your foot off the accelerator and it changed ratios, from high to low you did the same but blipped the throttle to make it change.

If you didn’t time it right there would be a few clunks from the back end!

M

 

[TheGrandWazoo]

There was a knack to it, from low to high you flicked the lever, took your foot off the accelerator and it changed ratios, from high to low you did the same but blipped the throttle to make it change.

If you didn’t time it right there would be a few clunks from the back end!

M

Bipping the throttle - almost like a crash gearbox!!

I think United Auto was a bit conservative so I suspect that this batch of Leopards was a divert (as often happened) so it seemed overly complex to them!

 

[CN04NRJ]

There was a knack to it, from low to high you flicked the lever, took your foot off the accelerator and it changed ratios, from high to low you did the same but blipped the throttle to make it change.

If you didn’t time it right there would be a few clunks from the back end!

M

I've driven a preserved Leopard coach with the split axle - it took a little getting used to and there were definitely a few clunks on my first few attempts!

 

[GusB]

Our "native" semi-auto Leopards all had the steering column electro-pneumatic control with single-speed diffs but, as a result of the Stagecoach takeover and the Inverness bus war, we ended up with a few imports from Cumberland (RRM-X) and a couple from Ribble (HNE-V) which had the two-speed diff. I don't think they were ever used as intended.

 

[Volvo142]

Three of Derby City Transport's batch of ten Volvo Citybuses were delivered as "dual purpose" vehicles which operated a combination of regular service and private hire work.

These three (B 141-143 GAU), had a switch under the stairs to enable/disable an extra gear. Once enabled, they were very fast!

 

[TheGrandWazoo]

Our "native" semi-auto Leopards all had the steering column electro-pneumatic control with single-speed diffs but, as a result of the Stagecoach takeover and the Inverness bus war, we ended up with a few imports from Cumberland (RRM-X) and a couple from Ribble (HNE-V) which had the two-speed diff. I don't think they were ever used as intended.

The Ribble HNE-Vs would have originated with National Travel (West) so were full coaches with a single door, so made sense for a high-speed diff as they hammered down the M6.

 

[CBlue]

Not so much a key, but a local independent purchased a brand new (at the time) B7TL/East Lancs which had a mode switch by the gear selector for the engine management and gearbox. It could be changed between between "Economy" and "Power" which raised the rev limit on the gearbox between shifts, along with making the kickdown more sensitive. Never had issue making progress in power mode!

 

[Justin Tyme]

I recall a Private Hire trip on a West Midlands Travel Volvo B10M bus (one of 1055-1060, new in 1986) where the driver had a key to enable top gear.

As regards semi-auto Leyland Leopards with twin speed rear axles, Midland Red had a batch of 20 in 1974 (299-318) - the only ones that company had, I believe. They replaced the BMMO CM6Ts, which were very fast, so I imagine the twin speed axles were a way of trying to improve performance towards CM6T standards.

 

[RJ]

Not so much a key, but a local independent purchased a brand new (at the time) B7TL/East Lancs which had a mode switch by the gear selector for the engine management and gearbox. It could be changed between between "Economy" and "Power" which raised the rev limit on the gearbox between shifts, along with making the kickdown more sensitive. Never had issue making progress in power mode!

Sounds handy - might look to get something like that installed on my fleet! Did those buses happen to have a Voith transmission?

Pretty sure the circuit boards on mine have 5th/6th gear inhibit functions, but they're not in use - don't see the point.

 

[CBlue]

Sounds handy - might look to get something like that installed on my fleet! Did those buses happen to have a Voith transmission?

Pretty sure the circuit boards on mine have 5th/6th gear inhibit functions, but they're not in use - don't see the point.

5 speed ZF if I remember right. Flick the switch and 62mph was achieved with relative ease....

 

[Devon Sunset]

I'm sure the S9**AKS that First Edinburgh received new had this facility although I can't say if it was ever used.

 

[GusB]

I could be misremembering, but I'm fairly sure that I can recall one of Bluebird Buses' drivers saying something about top gear being locked out on some of the original Volvo B10M / Plaxton Interurbans.

That batch (K-GSA) were dedicated to the 305 (now 35) route, so the speed limit was never higher than 50mph, but I would have thought that fuel economy would have been more important than restricting top speed.

 

[Taunton]

For those too youthful to remember ( ) this was an automotive style that came along in the 1950s, called Overdrive on cars, and Two-Speed Axle on coaches. It was an electrically-operated two ratio rear axle differential, done with a small switch on the gearstick or elsewhere, essentially another gearbox, which typically could only be operated in 3rd and 4th gears, at a time when vehicles commonly only had four gears. Quite why it was done this way rather than further ratios in the gearbox is something an engineer will have to explain. High end cars (only) like the Triumph 2000 in the 1960s-70s had it as standard, and it was really motorways coming along that developed it. I believe the first coaches to have it were the Midland Red ones that ran on their pioneer M1 motorway route from Birmingham to London; they were built by the company themself, and had all the West Midlands motor industry suppliers on their doorstep to develop it. 85mph apparently was not unknown with them, rather on the edge given the brake and tyre technology of the times.

 

[Geoff DC]

2 speed axles were common on trucks too. It effectively gave you a High & Low ratio for each gear, so a 6 speed box with 2 speed axle gave you 12 gears, this was also useful in hill climbing as you could change down half a gear at a time.

There were also gearboxes where the high & Low ratios where in the box itself.

Another commercial option is the range change box, where you have 2 or 3 ranges on a typical 4 speed H arrangement and maybe a splitter as well

The graphic below shows the gearshift pattern for the Eaton-Fuller transmission.

 

[CN04NRJ]

2 speed axles were common on trucks too. It effectively gave you a High & Low ratio for each gear, so a 6 speed box with 2 speed axle gave you 12 gears, this was also useful in hill climbing as you could change down half a gear at a time.

There were also gearboxes where the high & Low ratios where in the box itself.

Another commercial option is the range change box, where you have 2 or 3 ranges on a typical 4 speed H arrangement and maybe a splitter as well

I recall driving some B10Ms with an electrical switch on the gearstick - although they were all elderly and stuck in high or low ratio. The one stuck in high ratio was awful at hill starts!

 

[RJ]

5 speed ZF if I remember right. Flick the switch and 62mph was achieved with relative ease....

Nice - must have the 250bhp variant of the engine.