The EC-630PP HMC - Haas - Haas Automation, Inc.

Velvet Slippers
Unless you’re a space shuttle pilot (or a fellow drag
racer) you probably can’t imagine accelerating from 0 to
60 mph in less than 1 second, or for that matter, from 0 to
250 mph in less than 6 seconds.
“At the start, we’re pulling approximately 4Gs (four
times the force of gravity),” says Ulf. “It takes a year or two
to get used to the violence of the first couple of seconds.
During that time, you’re not really driving, you’re just
holding on and keeping the throttle pressed to the floor.”
Which is made easier by the presence of a metal restraining
stirrup over the pedal – a practical consideration, given the
explosive force of a launch.
It’s non-driver Jörgen Leanders who is responsible for all the
clever engineering on the car, including the all-important clutch.
It doesn’t matter how skilled the driver is, the biggest
challenge is getting the power down to the asphalt. Since
electronic launch controls are banned, it’s down to a slipper
clutch to transfer power quickly and smoothly.
“A slipper clutch partially disengages to regulate the
amount of engine power delivered to the wheels,” explains
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Jörgen. “However, because the clutch uses friction to do its job,
the pads are prone to serious wear, so we need to be able to
quickly strip and reassemble the clutch, often between runs.”
In most racing situations, clutches are made in
aluminium to be as small and light as possible. In an F1 car,
for example, they’re designed to last just long enough to get
the car to the end of the race. Bolted-steel segments help
dissipate the heat, but they flex and bend, and can quickly
fail. In drag racing, the clutch has to transfer a huge and
violent surge of power, so the aluminium is replaced with
titanium, which is tougher but heavier.
The Leanders clutch uses a floating-plate system in place
of bolted segments, which improves heat dissipation and
makes it easier to take apart and rebuild after a run.
In the corner of the Leanders workshop, surrounded
by glass-fibre vehicle body parts and semi-used balloon
tyres, sits a brand-new Haas EC-400 horizontal machining
centre. Bolted to one pallet is the aluminium base of a halffinished
clutch.
“We mill just about everything on the clutch, except the
bolts, some small axles that hold the fingers and the adjusting