4PK serpentine belt conversion for a TR 3A

[TonyB]

This thread tells the story of converting a 3A tractor fan belt to the popular modern four ribbed flat belt and is a follow on from the thread I started last year entitled harmonic damper and thin belt conversion, which it seems is still going. In brief I abandoned the idea of fitting a harmonic damper for two reasons: 1 expense and 2 insufficient evidence that the ones I could afford actually did anything, for a Road car anyway. Having decided that it seemed like I was going to go down the cheap route so I decided not to buy an alternator either. I had no trouble with my dynamo and didn't go out in the dark anyway. I like to be tucked up in bed by nine. So, all I had to do was make it so that my dynamo could be adjusted to tension the belt without (the dynamo) fouling my four branch exhaust.

A serpentine belt seemed to be in order. Fit, run for twenty minutes, adjust and forget. It should last me out anyways. Rather than do something sensible like draw it all out and make the pulleys to fit a particular size of belt I decided to make the pulleys then find a suitable belt; they do after all come in a good range of sizes. Below is a photo of the finished set up.

 

I shall break this up into several (lots?) of posts because I typed a load out and lost it all so this way I'll only loose a bit at a time

 

Tony

[RogerH]

Hi Tony,

that looks neat. It should never squeal as do some of the normal V belts.

I like the idea of reverse engineering - start with what you want then work backwards to achieve it.

 

 

If you type out your text in 'Word', you can then copy and paste into the forum post. That way it will not get lost.

 

Roger

[TonyB]

So, all it cost me was around $35 ish for the belt and I bought $30 of machine grade aluminium from the metal recycler which I didn't end up using so I need not have spent that. The first thing I did was look up the specifications for a 4PK pulley and grind up a suitable single point tool for cutting the grooves. I relied on my lathes graduated collars on the feed screws for spacing them. The first pulley I attacked was the water pump. It went against my nature but in the end I mutilated the original pulley by turning the back off and locktiteing on a piece of aluminium for the 4PK belt

 

Photo: turning off the back of the pulley but leaving on the front flange as a register.

 

 

The completed pulley fitted.

 

Ever wonder what the two little ramps cast into the pulley face are for? I reckon they are for holding the pulley still whilst undoing the retaining nut. At last, that's what I used them for. I made up a tool to press against the pulley face to stop it rotating. It's a shame it doesn't work for doing the nut up though.

The modified pulley diameter is much the same as the original.

[peejay4A]

The washers on the timing chain cover look interesting.

[TonyB]

Oh dear, the first photo didn't appear. Try again

 

 

Turning the back off the water pump pulley

[TonyB]

Yes Pete, I'll get to the washers in a bit. Thanks for noticing,

This is hard work for my Luddite of a brain, only 5% battery on the I pad left now. I'll do some more tomorrow

 

Have I got word on a iPad Roger? Beats me.

 

Tony

[RogerH]

Whats an Ipad !!

 

I must upgrade from my Sinclair Z80

 

Roger

[Lebro]

6 jaw chuck, that's posh !! Nice tool post.

 

Looks like a good project, & well executed.

 

Bob.

[TonyB]

Roger, remember when we were at school and used a slate and a lump of chalk? Well, an I pad is similar but you don't use a lump of chalk, you use a finger. It still breaks like the slate if you drop it or stand on it but is a lot dearer to replace. I believe they are known as tablets in modern parlance, named after tablets of stone upon which one wrote with a hammer and chisel. Sometimes it feels like writing on stone with a hammer and chisel would be quicker and you wouldn't get what I like to call "iPad finger"

 

Bob, that is a Pratt Burnard six jaw "grip true" chuck. Each jaw is individually adjustable to enable perfect concentricity for a given diameter allowing for repeatability when using stock of that diameter. It still works like a scroll jaw chuck though for chucking and unchucking, unlike an independent jaw chuck. I'm sure you know what I mean. Yes it is a nice tool post. Before I got this lathe I struggled with a two way tool post and bits of packing. I bought the lathe from the estate of a very dear friend who died a few years ago. He made the tool post and the holders. He was a fine engineer and machinist. Thanks for the compliment.

 

Tony