Education

"Cé hé sin" (michael-m-mouse) 07/10/2016 at 17:04 • Filed to: Mercedes, Hydrak

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We’ve met a weird transmission recently.

Meet another.

Mercedes used the Hydrak (hydraulische Kupplung) in the late 1950s. Like the Saxomat system with which it shared part of its design it used an electrically controlled and pneumatically operated automatic clutch for gear changing and in this case a fluid coupling for starting. To change up or down you just lifted the accelerator and moved the gear lever (mounted on the column in this case because 1950s) whereupon a switch activated the clutch for you. To start and stop you just used brake and accelerator. Why not just use a conventional automatic? Because the Hydrak was cheaper to make and was being sold to buyers unfamiliar with automatics so they had no frame of reference.

In the event it turned out to be a failure, being both unreliable and subject to driver abuse, and used cars with it were so hard to shift that for years afterwards Merc dealers used to carry manual conversion kits*.

Mercedes abandoned the idea but similar transmissions were used by VW and Porsche for many years afterwards.

*containing this little lot, as per !!!error: Indecipherable SUB-paragraph formatting!!!

Flywheel
Clutch disc
Pressure plate
Clutch release bearing
Complete bell housing with release fork and cover plate and any other items attached
Transmission input shaft
Transmission cover front
Front half of drive shaft
Clutch pedal with linkage and return spring
Shift lever
Shift linkage
Annular nipple (vacuum fitting on brake booster) you could plug the line to the vacuum container.
You may need to change the alignment pins between the engine and bell housing.

Flyboy is FAA certified insane > Cé hé sin 07/10/2016 at 17:43

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Haha

Annular Nipple

kanadanmajava1 > Cé hé sin 07/11/2016 at 05:29

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Interesting. I didn’t know that M-B used this kind of system.

My Packard had originally an automated clutch pedal. At some point it has been removed and all that is left is a red clutch pedal and a complicated accelerator mechanism. Unlike M-B’s system this used vacuum to power it and it was was pretty much only bunch of additional switches and actuators mounted to the normal clutch and accelerator mechanisms. It could be disabled with a switch.

For some reason our internet security system doesn’t like your link. It reports the link being “harmful”.

Cé hé sin > kanadanmajava1 07/11/2016 at 06:34

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Many German makers used variations of this system - Saxomat, Hycomat and Hydrak - in the 1950s and 1960s partially because there were many disabled drivers after WW2.

Surprisingly Lancia used the Saxomat for a while.