60s Semi automatic gearbox?

[chas_n]

Sorry, I know nothing about buses, I'm hoping someone on here can explain something for me, that I was trying to explain to a friend when reminiscing.

As a child in the 60's in Walsall, I remember the then very exciting new buses with front entry and flat fronts - maybe Daimlers? This was the time of the blue buses, before WMPTE. You could sit in a front seat and watch the driver, and he used some sort of gear selector that was a kind of switch with a short handle and spherical knob on the left hand side of the steering wheel, moving in a standard H-pattern. I think this was then new, as I think the older rear entry buses with separate driver cabs typically had a standard gear lever and clutch - maybe I'm wrong about that though.

My questions are
- Roughly how did these gears work? Was the 'switch' electric or hydraulic? (I don't see how it could be a mechanical linkage, really).
- Was it a semi-automatic gearbox that changed gear as he moved the switch, or was it some sort of pre-selector activated by a button or pedal?
- Did he have 2 pedals, or was there also a clutch?
- Do modern buses use this type of mechanism, or was it a short-lived phenomenon?

Hope you can help a total ignoramus.

 

[GusB]

Sorry, I know nothing about buses, I'm hoping someone on here can explain something for me, that I was trying to explain to a friend when reminiscing.

As a child in the 60's in Walsall, I remember the then very exciting new buses with front entry and flat fronts - maybe Daimlers? This was the time of the blue buses, before WMPTE. You could sit in a front seat and watch the driver, and he used some sort of gear selector that was a kind of switch with a short handle and spherical knob on the left hand side of the steering wheel, moving in a standard H-pattern. I think this was then new, as I think the older rear entry buses with separate driver cabs typically had a standard gear lever and clutch - maybe I'm wrong about that though.

My questions are
- Roughly how did these gears work? Was the 'switch' electric or hydraulic? (I don't see how it could be a mechanical linkage, really).
- Was it a semi-automatic gearbox that changed gear as he moved the switch, or was it some sort of pre-selector activated by a button or pedal?
- Did he have 2 pedals, or was there also a clutch?
- Do modern buses use this type of mechanism, or was it a short-lived phenomenon?

Hope you can help a total ignoramus.

Welcome to the Forum!

I'm not technically-minded enough to be able to explain how the actual transmission worked, but I can give a general idea. Others may be able to go into more detail.

The gearboxes themselves were epicyclic, and used some kind of pneumatic system to change the gears. Some had electropneumatic control (little lever generally mounted on the steering column), while other used direct air control (used on later Leyland Atlanteans, for example).

The driver only had two pedals to deal with, and the gearboxes could also be adapted to work automatically. I think Daimler used a system called Daimatic (not too clear on that, TBH), while Leyland used G2 and then the later LVA45 for their automatic versions.

Leyland also used a system called Hydracyclic, which used oil pressure instead of air. This was standard on the Titan, Olympian, Tiger and Lynx, although operators often chose other transmissions, eg Voith, ZF.

I don't know of any manufacturers that use transmissions like these any more. Most modern buses will have Voith, ZF or Allison transmission, and there is also now a trend towards automated manual transmission (ZF Astronic, Volvo i-Shift).

 

[Mr Manager]

A couple of links that may help you

https://en.wikipedia.org/wiki/Self-Changing_Gears


https://en.wikipedia.org/wiki/Preselector_gearbox

 

[chas_n]

That first link on self-changing is very informative and absolutely relevant - I did read the other pre-selector one before my original post, but it didn't seem to fit with what I remember.

So probably the buses I am talking about are:
http://www.wythall.org.uk/vehicles/vxdh516g.asp
The caption says this is a Daimler Fleetline CRG6.

I'm sure from the Wikipedia self-changing gear article that this is what I was looking at - but it says that the lever could be either electric or pneumatic (in either case, actual gear change was, according to the article, pneumatic). It doesn't really matter, but does anybody know whether the Daimler Fleetline used pneumatic? Actually, I would say that I might remember it that way - perhaps a slight pfft sound when changing gear - it was a long time ago, but I was certainly fascinated by the new technology in these shiny modern looking things (compared to the old ones, which might have been Guy Arab III, judging by google searching). Also, steering looked so effortless. I was very young.

 

[GaryMcEwan]

Have a look at this video...

Watch this...

 

[GusB]

That was an interesting video, Gary. I knew you weren't supposed to slam straight from one gear into the next, but that was the first time I've seen the reasons properly explained.

I've witnessed many a driver change through the gears without lifting his foot off the throttle, most notably in the bigger cities like Aberdeen and Glasgow, but quite a few of our local drivers did it as well.

I wonder if preventing this sort of abuse was the main reason for Edinburgh using fully-automatic control instead of semi-auto.

 

[chas_n]

Terrific video. What a good forum this is. So that pretty much explains it to me. Though in the particular case I remember, the gear change was on the left of the wheel, the gear stick was shorter, there was less plastic, and the gate was metallic and open to view as a distinct H, like on a Ferrari (not that I've ever driven a Ferrari, but like Ferraris I have seen on Top Gear). On this one it's all concealed under a rubber boot, I think. Not obvious to me whether the selector in the video is electric or pneumatic, but I'd guess electric.

Still, obviously the same technology, and a good explanation of how the gear box works as well - essentially like a car automatic gear box, but with pneumatic actuators for the bands.

Thanks again.

 

[Cowley]

An interesting thread chaps. I also remember similar gear changes from back then. Did old BR DMUs have a similar system?

 

[GusB]

Terrific video. What a good forum this is. So that pretty much explains it to me. Though in the particular case I remember, the gear change was on the left of the wheel, the gear stick was shorter, there was less plastic, and the gate was metallic and open to view as a distinct H, like on a Ferrari (not that I've ever driven a Ferrari, but like Ferraris I have seen on Top Gear). On this one it's all concealed under a rubber boot, I think. Not obvious to me whether the selector in the video is electric or pneumatic, but I'd guess electric.

Still, obviously the same technology, and a good explanation of how the gear box works as well - essentially like a car automatic gear box, but with pneumatic actuators for the bands.

Thanks again.

The electro-pneumatic controls were originally mounted on an extension of the steering column, as you described. There was a distinct "H" and the gear lever itself was a short stalk with a little ball on the top.

Source: http://www.busaustralia.com/forum/viewtopic.php?t=47752&f=4

You'll notice that there's another little "ball". This had to be pulled out to release a pin that prevented accidental engagement of reverse.

Later versions had a different gear lever and could be mounted on the driver's left, usually on a pedestal, or on the right in which case it was usually built into the console. If you look closely at the video you'll see that there is still a visible gate on the lever on the Leyland National.

Source:
http://www.volvodemort.com/technical/volvo/manuals/operator/b58/page028.html

 

[chas_n]

Yes, yes. That's it. Perfect! Ridiculous that I have no idea where I left my glasses 5 minutes ago, but remember that so clearly from nearly 60 years ago.

 

[Bletchleyite]

An interesting thread chaps. I also remember similar gear changes from back then. Did old BR DMUs have a similar system?

Essentially, yes (I've driven one at Wirksworth). Except for that the driver's control is sequential rather than an H-gate.

 

[philthetube]

I used to drive Bristols and Seddons, (Worst bus ever), which had a gate opposite the Reverse slot which opened the doors, this had the advantage of ensuring the bus was taken out of gear when at stops.

 

[deltic1989]

I remember very fondly spending many a school holiday riding around Lincoln with my Dad on buses fitted with this type of gearbox. In fact it was such a regular thing that the bosses at the time presented me with a Road Car tie, that I still have somewhere.

I seem to remember that the accepted method of changing gear was click - 2 - 3 - click. However I also recall that many a driver didn't stick too well to that, and committed all the sins that that video describes.

Another memory that comes to mind took place in New York City, when at one point the city tour operators used Ex-UK open top buses. I think the one were on was a Bristol VR however I could be wrong. I remember Dad wincing at every gear change as the driver slammed it between gears. When we got off Dad spent 5 mins advising the driver of his errors, which as you can imagine went down like a lead balloon.