Found on a F1 car in 1980s, maybe it is a JPS Lotus. Why such design is applied?

RDV nailed it in the recent "horizontal rear calipers" thread:

"The reason for the rash of twin calipers was the additional capacity for heavy braking with improved tire grip, which in turn needed increased pad area, which brought on severe pad wedging as the longer pad "tilted" on the single piston, as constrained in 13" dia. rims, not to mention caliper flex as the "bridge" got longer...eventualy twin piston calipers (now even three piston...)with different size bores on the leading and trailing edge of pads and better engineered calipers (FEA helped there..) solved the problem, and voila..."
http://forums.autosport.com/index.php?show...lipers&st=0

There have also been some twin caliper setups on production cars over the years for roughly parallel reasons. M-B, Bentley, Audi, Maserati, surely some others...

A question that came to mind when reading RDV's reponse the first time: How long between the need for increased braking capacity and the introduction of multi-piston calipers? That seems so...obvious, over building larger and larger single-piston calipers. Of course, I have the benefit of hindsight, but still.

Works Factory rally Escorts had twin rear calipers one set being for separate hydraulic handbrake use.

A friend of mine had a Datsun 1000 sports sedan with a Holden Red 6 cylinder in it and he ran twin calipers at the front because he ran 13" wheels and theres only so big a disc you can fit inside a certain sized wheel.

I thought we'd been through all this...

Is that a carbon disc?
Cheapracer, I have had a car with brakes like that but couldn't see the purpose of carrying the extra weight so I re plumbed and did away with a pair of calipers. Any idea why they were like that?

I hope you took one away each side, not two on one side...

Apparently the French and Italians wanted the extra calipers for their tarmac rallying which I can understand, getting a wide slick locked up consistently when you can't always get the weight off the rears can be a pain - mostly not needed on dirt though, I just used to always run the rear brake line through the handbrake mastercylinder as you probably did.

One each side Tony, wouldn't want to mess up the cornerweights!
Wide slicks and tarmac make sense, not so convinced using the handbrake much is an advantage in those circumstances though.

Serious? In French Mountain roads?

Upon winning the 1982 Monte Carlo Rally, as can be seen in his interview in the Duke video wrapup for that year, Walter Rohl attributed the win to the Ascona's fantastic handbrake!

That's a relief, I've been worrying...

I suppose those roads have a surplus of hairpins, not a hairpin fan myself. Rohl had a preference to have his cars set up with understeer and tended to have the handbrake as a sort of "get out of jail free card". I suppose the more variable and unknown nature of even tarmac rallying means that there is much more of a requirement to be able to generate extra car rotation than in circut racing, generally less width as well. As an experiment it would be interesting to set two cones a reasonable distance apart and time a few laps using and not using the handbrake, I understand that when rally schools do this without is quicker.