Looks a bit like something for an Unclear Reactor?






I'm not totally sure it will work - but the numbers seem to add up. I have some double lip piston seals on the way as well as a 12v 5 port open centre valve to drive it.



At 120psi, there should be 920lb of force on a master cylinder which I reckon is about equivalent to 200lb of force on the foot brake (with it's mechanical advantage). That should give about 2000psi in the brake lines which should be enough to stop a wheel!

Si

Switch operated 'fiddle' or 'steering' brakes. Another excellent idea! Though with this design, you will need separate calipers on the axle. If you use master cylinders which would normally have separate reservoirs connected via proper brake pipe fittings(eg hillman imp type) you can run the main brake line into the 'in' port, and then to the normal caliper via the 'out' port. When the fiddle is operated, the piston closes the 'in' port so pressure only goes to the one brake. When the fiddle brakes are not operated, the brake pedal will work normally, as the pressure passes through the fiddle brake master cylinders. You would need to make strong stops for the pushrods to prevent the guts being pushed out of the master cylinders when the foot brake is operated. might be easier to use 2 separate cylinder units for that though.

Regards,
Diff

Doh! Too easy!

I'm thinking about a couple of push buttons on the underside of the auto selector lever to lock up either side, with a lockout if the rear ARB is engaged. I'd like to do 4 wheel fiddle brakes - but finding space for the calipers on the front is a bit tricky.

The pneumatic idea came about because there is nowhere obvious to stick the levers in the cab. I considered making a split pedal (like on tractors) to go where the clutch used to live - but was persuaded by Simon C that a more complicated solution is always better

Si

Looks like a great idea to me been toying with the idea of fiddle brakes. But didnt really fancy having the two leavers in the cab, and the possibility of using them with the arb in this is a great solution

Nice idea, Si. I'll be interested to see how it works out.

FYI, I was also tought an interesting trick with your hand brake a little while ago by JST; unlock the centre diff and engage the hand brake to allow you to turn tighter....

Will
I've heard that is the quickest way to destroy the centre diff.

Nice idea, but IIRC fiddle brakes are illegal if fitted to a Road vechile ?...even if disengaged

Nice work and thoughts tho Simon as usual

Nige

I thought they were ok if they worked on a seperate system. ie not through your origional master cylinder. i may be wrong though, meaning it would be legal if you had a second set of calipers mounted to the rear discs.

I wondered where this thread had vanished to!

It is correct that it is illegal on the road, but only if it changes the balance of the service brakes. If it is an entirely separate system with separate master cylinder(s) and slaves / calipers it's ok.

Where this becomes important is skid steer vehicles such as tanks, argocats etc. They must not use the service brakes for steering - but separate is fine even on the road if road registered.

I don't think I'll be using them much on the road however - not being too keen on dying!

Si

yea let us know how it goes, im really interested in this one. might even be cheaky and try and persuade you to build one for me if it works

I'm assured I'll get the piston seals and valve tomorrow - so shouldn't be long before the first live test!

I'm looking at the moment (amongst other things) at making a bolt-on adaptor for fiddle brakes with a thin (3mm) plate bolted between the stub axle and axle case and another 8mm thick bracket which locates on two extended stub axle bolts behind the flange on the axle tube forming a sandwich at the caliper mounting bolts, drilled to accept RR rear or 110 front calipers. For hand operated levers, 110 calipers are better as they give twice the mechanical advantage of RR Rears.

It seems to be the fabrication and welding of the brackets which floors most people!

It would be nice to produce a complete bolt-on kit which can be used with the milner levers or air over hydraulic as suits.

Si

Never mind all this nonsense, I need a series disc handbrake NOW.


Les.

I need to borrow a series transfer box to complete the design! I was planning on buying one at Sodbury and trying to have full scale manufacture before Billing!

If you happen to have one you could stick in an envelope.....

Si

I've got a few transfer bioxes Si, but you are rather a distance from me.


Les.

These are the Mk2 bracket design - thought I'd go & do measuring & figured the sandwuch idea was rubbish. These will probably be laser cut with the rebate machined in. They take RR rear calipers or 110 fronts and just bolt on to 3 of the M10 bolts which hold the stub axle on. This gives a stronger mounting to the axle than to the caliper - and the caliper mounts are clearly up to the job.

Any of you know the thread size of the bolts used to hold calipers in place? The RR ones are different to the 110's. Although I have calipers, I don't have any bolts and my thread gauge will not fit down the hole!

Si, I will Park the IIa in your garden tonight or tomorrow night if that helps...

Mark

Thanks Mark - I've winched the 90 in to the garage (using my mill as a ground anchor!) so the drive is clear. Could you stick it beside the garage on the rubber matting next to the Air Con pack?

Cheers,

Si