pivot pins

[smithhymac]

Hi all, I'm looking for a bit of technical advice on which steel would be suitable to machine new pins from for my project JCB 3, I'm looking for a grade of steel ideally easy machinable yet hard wearing without heat treating if possible.
I have spoken to a few engineers locally and they seem to suggest en36T or en24T, but on research both seem to need heat treatment!
Does anybody have advice on this? I plan to machine the pins myself and steel being expensive, I'd rather not make a mistake.
Regards morgan

[Osgood]

Bent pins can be a pain to remove. I imagine that JCB pins would be sized to be 'big enough for the job but no more', in which case it might pay to get a local heat treatment company to take your machined pins and do what is necessary.

In situations where the pins are more generously proportioned (e.g. 2 1/2" dia plus pins on 70's generation wheel loaders) , I have had great success with a combination of hard chromed hydraulic ram rod (which is probably EN24T or better) for the pins, and hard grade nylon bushes (available from several suppliers machined to your requirements).

[smithhymac]

I've sourced all new bushes which are the original spec spring steel design, the JCB has 1:3/4" diameter pins and my initial plan is to bar bright bar this size if possible so machining will only concern facing the ends putting a chamfer on them ,then boring a grease way through the middle and thread for a grease nipple. I'm just trying to work out which steel to buy really, and any ideas are greatly appreciated.

I've totally stripped down the machine, all pins are out and some needed cutting out with the gas, it's been a big job!

[wiggy]

try looking on line for hydraulic ram makers
ud b suprised how much hard crome rod they have laying around in off cut lenths
quite a bite is actualy hollow so just weld end caps on
or if its solid just buy a desent drill bit on ebay ect
ud be suprsied how cheap you can make pins or even buy them ready made
its the bushes that can be dificult and if you have bought these
be aware some bushs you fit and then have to ream out but dont think its a problem on j c bs

[Jeremy Rowland]

Morgan I would use EN24T it is a better grade for this application that EN36T I would not worry about heat treatment but would ensure that once you have drilled through and cross drilled your grease holes that you mill a shallow slot along the pin through the grease hole or better still around the pin in a cross type pattern if you have a rotary head for your milling machine (assuming you have access to a miller).
At my work we would use EN36T if we intended to get the component heat treated and then you would need to leave approx. 0.025" of excess material on the pin that then needs to be ground off after the heat treatment; just use the EN24T without the need to heat treat, it should suit your application without any problems.

Jeremy

[smithhymac]

Brilliant Jeremy that exactly what I wanted to hear, I was just not confident in the knowledge I had!
Hope all is well, happy new year!
Morgan

[smithhymac]

PS, I've just purchased a Colchester triumph 2000 lathe and this will be my first real project with it!

[tctractors]

Why do you need to make your own pins, even the 3CX uses 1"3/4 pins, the rear bucket pins are very cheap non OE and can be drilled, it would hardly be worth messing about, the pins in JCB are fairly standard spec so this would be easy to sort a pin/s to match.

tctractors

[FOWLER MAN]

Why do you need to make your own pins, even the 3CX uses 1"3/4 pins, the rear bucket pins are very cheap non OE and can be drilled, it would hardly be worth messing about, the pins in JCB are fairly standard spec so this would be easy to sort a pin/s to match.

tctractors

Hi Tony,
Those were my thoughts too.
Seemed so obvious I thought I must be missing something.
Happy new year.
Fred

[smithhymac]

As its a restoration rather than a working machine I want the machine to be as it once left the factory and the modern pins have the grease nipple on the eye and are solid, where as the pins particular to this machine have the grease nipple in the pin itself, so to fit modern pins I'd have to drill and tap nipples that are fitted on the eyes on the movement, and it would not be correct. I know this is a little over the top but its also a project I'd like to do so I can say I have! I've made new ram rods and feel quite of an achievement in this, its not my trade I'm just a farmer.
Hope you get what I mean, regards morgan