Hobbs 'Mechamatic' Gearbox

[RH1300S]

Having just read an interview with David Hobbs, I'm interested to know more about the Hobbs 'Mechamatic' Gearbox invented by his father.

I've Googled, but struggle to get more than outline info.

Does anyone know the detail of how it worked?

I'm guessing we have at least one member here who will know this....

[Belatti]

Yep, and will probably say that its 19th century is crap compared to his design

[autogyro]

Not so Belatti.
I have worked on the Hobbs Mech-Matic transmisions and replaced them with the Borg Warner 35 transmission in road cars.
It was a four speed epicyclic automatic gearbox that used 2 and 3 plate clutches that were engaged with rubber bags.
One clutch also did direct engagement, so no torque converter or fluid flywheel.
They were very unreliable and difficult to set up the control system, also there was little support from the manufacturers and little if any paperwork if I remember.
The racing successes by Hobbs in the Lotus Elite where because there was no conventional clutch, the shifts were fast and there was less torque loss in the geartrain. In production they were nick named 'Jerkomatics' which explains why they did not achieve success in road cars. They were also unsuitable for high performance engines because of the small clutch design.
Colin Chapman drove an Elise with one fitted. He liked the idea but realised it would not be practical in heavier race cars with more powerful engines.
The work I did with the Automotive Products bevel epicyclic automatic as fitted to the Mini was a better direction. This involved modifying the hydrolic valve chest and governor system to give 5 speeds instead of 4, fitting an electronic shift mechanism and replacing the torque converter with a clutch with extra radial shock springs to soften the shift. I built an official version of this for Leyland and a racing version with a very low diff ratio still holds the lap record on the oval at Bovingdon raceway under test. Barry Lee tested the car at Brands Hatch.

http://tinypic.com/usermedia.php?uo=Mib ... 3GrQ%3D%3D

[RH1300S]

Thanks for that Autogyro - I thought you would come up with the goods. I wonder whether this triggered Chapman's desire to develop the 'queerbox'?

So, a clever idea not well executed?

Do you know if any drawings exist on the web?

P.S. - Thanks for the link, a good read. Well done for actually making and racing something

[ringo]

Not so Belatti.
I have worked on the Hobbs Mech-Matic transmisions and replaced them with the Borg Warner 35 transmission in road cars.
It was a four speed epicyclic automatic gearbox that used 2 and 3 plate clutches that were engaged with rubber bags.
One clutch also did direct engagement, so no torque converter or fluid flywheel.
They were very unreliable and difficult to set up the control system, also there was little support from the manufacturers and little if any paperwork if I remember.
The racing successes by Hobbs in the Lotus Elite where because there was no conventional clutch, the shifts were fast and there was less torque loss in the geartrain. In production they were nick named 'Jerkomatics' which explains why they did not achieve success in road cars. They were also unsuitable for high performance engines because of the small clutch design.
Colin Chapman drove an Elise with one fitted. He liked the idea but realised it would not be practical in heavier race cars with more powerful engines.
The work I did with the Automotive Products bevel epicyclic automatic as fitted to the Mini was a better direction. This involved modifying the hydrolic valve chest and governor system to give 5 speeds instead of 4, fitting an electronic shift mechanism and replacing the torque converter with a clutch with extra radial shock springs to soften the shift. I built an official version of this for Leyland and a racing version with a very low diff ratio still holds the lap record on the oval at Bovingdon raceway under test. Barry Lee tested the car at Brands Hatch.

http://tinypic.com/usermedia.php?uo=Mib ... 3GrQ%3D%3D

How is this accomplished with no change to the gears. This was a planetary system correct?

[autogyro]

Planetary gear sets or epicyclic ringo.
A planetary gear set is far more efficient than a layshaft mounted gear set.
Planetaries have higher burst loads, less oil windage a smoother less noisy operation. The problem and the clever design challenge is how to change from one set to another without excess complication and reduced reliability.

[ringo]

I was interested in how you got 5 speeds from 4 by modifying the governer without adding a gear set.

[autogyro]

By modifying the valve chest and adding an extra governer/selector valve port.
This directed secondary pump pressure to two apply components, the top and reverse clutch and the reverse brake band servo. This is a combination not selected in the standard control system.
It also required the removal of the primary planetary set sprag or one way clutch, to allow the planetary casing to rotate in the oposite direction and braking of the primary planetary casing in reverse apply had to be achieved by using the third brake band instead of the sprag.
The result is a new first gear at a lower ratio to the conventional first.
Fitted in a mini with a diff ratio of 5.3 to 1, it gave almost instant auto shifts with no more than 450rpm from launch to 90mph, with fantastic acceleration.
With below 200 bhp the car still needed 9 inch wide slicks and extra trailing bars on the front suspension arms to prevent the tie bars bending on take off.
The engine was always 'on' the cam (649 LST with offset rockers)and would out lap anything at the time. I had hopes to continue but Leyland was in the process of failing. I could not afford to fit a unit into a different caseing for the Ford Escort of the time and in anycase I was busy with ideas for F1.

I did do the powertrain for this demon little car though, faster than many modern cars by a long way.

http://tinypic.com/usermedia.php?uo=OVJ ... mxoQ%3D%3D

[RH1300S]

Can we waver back OT briefly if possible? Does anyone have drawings of the Hobbs Design?

Otherwise, keep posting those links Autogyro - for me they make fascinating reading.

[ringo]

By modifying the valve chest and adding an extra governer/selector valve port.
This directed secondary pump pressure to two apply components, the top and reverse clutch and the reverse brake band servo. This is a combination not selected in the standard control system.
It also required the removal of the primary planetary set sprag or one way clutch, to allow the planetary casing to rotate in the oposite direction and braking of the primary planetary casing in reverse apply had to be achieved by using the third brake band instead of the sprag.
The result is a new first gear at a lower ratio to the conventional first.
Fitted in a mini with a diff ratio of 5.3 to 1, it gave almost instant auto shifts with no more than 450rpm from launch to 90mph, with fantastic acceleration.
With below 200 bhp the car still needed 9 inch wide slicks and extra trailing bars on the front suspension arms to prevent the tie bars bending on take off.
The engine was always 'on' the cam (649 LST with offset rockers)and would out lap anything at the time. I had hopes to continue but Leyland was in the process of failing. I could not afford to fit a unit into a different caseing for the Ford Escort of the time and in anycase I was busy with ideas for F1.

I did do the powertrain for this demon little car though, faster than many modern cars by a long way.

http://tinypic.com/usermedia.php?uo=OVJ ... mxoQ%3D%3D

I get you. Took me a while to understand. That's a lot of tinkering.
That article is like a prophecy.

[autogyro]

Can we waver back OT briefly if possible? Does anyone have drawings of the Hobbs Design?

Otherwise, keep posting those links Autogyro - for me they make fascinating reading.

I cant seem to find any further information on the Hobbs Gearbox.
Sorry, perhaps Mr Hobbs himself might help, I think he is still alive and involved with motorsport and the media in America.

http://tinypic.com/usermedia.php?uo=gEl ... rC9g%3D%3D

[Consul Capri]

RH1300S, I have a couple of original books/brochures that could be of interest to you, they are a 1963 parts book (exploded diagrams) this is for the Westinghouse version, as fitted to the Ford Kent 1200cc and 1500cc engines, and a more general 'how it works' kind of booklet (with great technical type illustrations). email ianthreethreefiveinghamatgmail.com change at to @ and don't spell the numbers!

[autodoctor911]

sorry to post another off topic reply, but the work on the mini gearbox interests me to the point of asking: What kind of physical changes to the valve body where necessary to achieve the extra ratio, and the desired quick gear changes?
Was a completely new control valve assembly fabricated, or where you able to use the existing casting?
I ask, because I want to know what kind of investment would be involved in doing a similar conversion to a popular rear wheel drive automatic gearbox, and which one would be best to use. I was considering something along the lines of a 4l80e GM or a 4r100 Ford, or maybe the NAG Chrysler/Mercedes.

[autogyro]

sorry to post another off topic reply, but the work on the mini gearbox interests me to the point of asking: What kind of physical changes to the valve body where necessary to achieve the extra ratio, and the desired quick gear changes?
Was a completely new control valve assembly fabricated, or where you able to use the existing casting?
I ask, because I want to know what kind of investment would be involved in doing a similar conversion to a popular rear wheel drive automatic gearbox, and which one would be best to use. I was considering something along the lines of a 4l80e GM or a 4r100 Ford, or maybe the NAG Chrysler/Mercedes.

The conversions I undertook on the Automotive Products APA transmission were over 30 years ago.
A new manual selector valve was machined to re-direct oil but the main conversion was to the main auto shift valve which in standard mode operates using a centrifugal governor balanced against a throttle position rod and detent spring.
This was remade using a seperate valve block with the extra ports for the new gear oil apply position and a new valve made with extra lands and facility for it to be moved either manualy or electricaly with a radial multi segment positioning motor instead of the mechanical centrifugal governor.
The AP box is/was very different from the modern 'clutch' boxes you mention.
It had brake bands as well as clutches (the original clutch plates and bands were phospher bronze and steel) with seperate servos which were easy to fit different feed piping to, there was also much more room to play with. The geartrain was/is a bevel epicyclic not the conventional spur and was much stronger more compact amd a better planetary concept all together. More costly to make though. The geartrain ran in engine oil with the engine.
There are competition conversions for modern auto gearboxes but modern units now have up to 8 gears anyway and the gains in rpm gaps would be minor. The torque converters are now more intigrated with the powertrain operation with lock up operation and the like. The modified Mini had no fluid link (the torque converter was not used) but used a conventional clutch. This can be achieved on any gearbox and many clutchflite units exist but the work involved in modern units would be great.
I could build another original Mini unit but I would prefer to use the geartrain in a lighter case.
Epicyclic geartrains are IMO much better than layshaft in many ways. It is the control systems that remain mechanical/hydraulic/electrical, which adds complication and reduces reliability. It also makes it hell trying to diagnose problems.

[Tommy Cookers]

....... most interesting !

presumably planetary box losses are only competitive with layshaft box losses in direct drive ?
(all-indirect layshaft boxes are indirect only once whatever the ratio, (eg) how are 3-8 speed planetaries ?)

(I know that's not the main point of this activity)

planetaries were established in bicycles 110 years ago, and were much more efficient than since planet bearing balls were deleted
planetaries were established in motorcycles 100 years ago
(but the motoring world chose layshaft boxes)