1964-1974 [Subscribe to Daily Digest] |
Okay, I scanned the diagram found on page 351-3 of the Sonett supplement to the service manual, and if I entered the link correctly it should show up with this post. If not, try clicking the link that should follow the post.
I'm not sure the diagram will tell you a lot, though -- there really isn't much to this system! Briefly:
-- The headlight pods are pinned onto a transverse shaft. When the shaft rotates, the pods go up and down.
-- There's a flat lever that sticks down from the shaft. This is what makes it rotate. The lever has a slot in the end opposite the shaft, and a spring that moves with it.
-- The slotted end of the shaft engages an angled bellcrank that pivots around a bolt through its "elbow," which attaches it to a stationary brace on the chassis.
-- The other end of this bellcrank is connected to the pullrod that runs back to the handle inside the car. The pullrod is just a tube with some bends in it.
When the headlight pods are closed, the pressure of the spring against the bellcrank holds the levers in the "closed" position. When you start to pull on the handle, the bellcrank starts to rotate forward against the pressure of the spring. When the bellcrank has moved far enough forward, the spring goes over-center, allowing the bellcrank to move the rest of the way forward. This action rotates the flat lever forward, twisting the transverse rod and causing the pods to rotate up. Now the pressure of the spring acts to hold the pods in the "open" position.
When you push in on the handle to close the pods, the reverse happens: the bellcrank moves against spring pressure until it goes over-center, pulling back on the flat lever and rotating the pods to the "closed" position.
It's a simple system that takes a firm pull. Why didn't SAAB use a vacuum or electric motor, like most other manufacturers? Well, ever notice how many old cars with hidden headlights have headlight actuators that don't work any more? Headlights are a safety system, and SAAB didn't want to take any chances with it -- so, a simple, mechanical system.
I don't know if it's true, but I've been told that the headlight control is a scaled-down version of the same basic mechanism -- a bellcrank acting on an over-center spring -- that was used to lower and retract the landing gear of the SAAB Model 91 Safir, a single-engine general aviation and training plane made by SAAB from the late 1940s through the early 1960s.
posted by 68.227.170...
, Sat, 6 Apr 2019 13:03:28
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