Really Silly Question For Mechanics Out There...

[Iggle Piggle]

Why are fanbelts (alternator/powersteering/water pump belt) not the toothed kind? That way they wouldn't squeal when they became worn !
Kind of an obvious question and probably has an obvious answer but I'm not seeing it.

Cheers.

(The first to answer this correctly wins the chance of replacing my fanbelt) :-)

[Hymie]

A toothed belt is used for the engine cambelt since the rotation of the engine and the cam must be kept in synchronisation. There is no requirement for synchronicity between the main pulley, water pump, alternator and power steering pump - so it is simpler to use a plain belt.

It would be possible to design a system that used a toothed belt, but his would add complexity, since if the belt were to stretch, the teeth would start jumping/slipping, resulting in rapid belt wear.

Ideally a toothed belt should be in contact with the pulley over at least 180 degrees, adding further complexity to the design; whereas a plain belt can cope with a little more than 90 degrees contact.

For some time now, Ford have fitted dual belts on their engines, such that should one fail, the engine will continue to operate normally.

[Iggle Piggle]

Fair answer, I was thinking (rare occurrence) that it may have been noise issues with the teeth or maybe cost of the pulleys.

[stocksman]

Simple answer - cost.

[TWR]

I agree with Stocksman. " Cost"

[TWR]

Iggle, to fit a new belt, 20 mins at the most. Don't get ripped off>

[mikey4444]

Can you still use a ladies stocking as an emergency fan belt repair, as my old Dad did many, many years ago ?

[Graham-W]

mikey4444. No you can't. Stockings were ideal for the old "V" type pulley but a stocking would fall off a multiple groove pulley they use today.

[mikey4444]

Well, it worked for my Dad's Austin Standard, in about 1961 !

[tonyav]

It worked on my 1970 3 litre Capri as well, mikey. ( future mother in law's tights ! ).

[Graham-W]

Both the '61 Standard and the 1970 Capri had V pulleys. Not the modern multi-grooved type. As for your mother-in laws tights..........

[Bazile]

hymie

//For some time now, Ford have fitted dual belts on their engines, such that should one fail, the engine will continue to operate normally. //

Which belts in particular and on which cars ?

[tonyav]

LOL, it was an emergency, Graham.

[tonyav]

For some time now, Ford have fitted dual belts on their engines, such that should one fail, the engine will continue to operate normally. //


Thats a new one on me to, Bazile.

[chas2008]

Poly v belts or multi toothed belts as they are called are more reliable and less prone to slipping, back in the early days race/rally/performance cars were upgraded to these belts, they were called poly V kits.
In the past drive/fan belts were far more prone to snapping its was common to carry a spare also hoses, neither of the items fail like they used to.