How Do My Rear Drum Auto Adjusters Work?

[ReganAndCarter]

Another question for the experts for my 2004 Fiat Scudo van 2.0 Jtd. No problems with brakes, just wanted to know how the auto adjusters on the rear drums work. I understand they ratchet slightly to make the shoes move outwards closer to the drum to take up wear. But what makes them adjust - is it each time the handbrake is used, or each time the brake pedal is pressed?

 

[Stivino]

I'm trying to keep it simple here;
When you pull the handbrake lever up it activates a lever within the drum which turns a ratcheted nut. If there is free play it will be ratcheted up to take up the slack.
video

 

[Burnerman]

More than once I give them a manual couple of clicks just to get a firmer handbrake.
If the brake drum gets a heavy wear or rust lip, the drums can be a pig to remove......some drums have a hole where you can get in with a screwdriver to back the adjuster off, otherwise its brute force - sometimes involving the services of a slide hammer
John

 

[ReganAndCarter]

Thanks, gentlemen. Think I understand it now - from Stivino's explanation. So if when you apply the handbrake the shoes aren't making contact with the drums, ie. there's a gap, the adjuster will ratchet - otherwise it will do nothing? Suppose that makes sense, because if they adjusted every time the handbrake was used they would soon lock up the drums. Clever little device.

 

[Burnerman]

Yep, you’ve got it.....trouble is, the ratchet only clicks once or twice a year so they can seize up. Ford use a ratchetting quadrant which is a bit more reliable.
I like rear drum brakes, although discs are becoming more common.....they are protected from the weather and can go for years without attention - although a regular clean out pays dividends. Its always a good move to lubricate all of the points where the shoes touch and slide on the backplate.
Unfortunately the shoe lining material can detach from the shoe if rust gets in.
John