Author Topic: Thwaites 2 Ton Two Cylinder Dumper Running On One Cylinder (Read 138512 times)

awemawson · « **Reply #50 on:** November 17, 2015, 07:22:04 AM »

So when the master cylinder is fitted all that remains to fix is the centre articulation pivot.

It's a rather complicated affair, with a 'lower bearing' that is just a spherical bearing bolted between two large lugs, and an 'upper bearing' that comprises a fish plate with spherical bearings inset at each end, with greasable pivot bolts going though both. Repair kits are available, but for silly prices - a tad under £300 each so that's not going to happen

The complication is getting the old bearings out to examine them and re-engineer them. The individual spherical bearings are only £15 or so each from bearing suppliers dependant on size but until removed sizes are only a guess.

Now this centre pivot holds the machine together - remove it and the front and back of the machine part company

So some method needs devising to support and contain the two halves - I may even temporarily weld bars across the pivot then just grind them off later.

awemawson · « **Reply #51 on:** November 17, 2015, 08:26:25 AM »

Well after lunch the new Master Cylinder arrived, along with the special oil. These dumpers have 'wet' (ie oil immersed) brakes, and the actuating cylinder and piston are inside the axle, so the hydraulic brake oil has to be compatible 'mineral oil' and not standard brake oil. In fact there is some thought that it might have been topped up with the wrong oil at some time hence jamming up as the seals swell - if that's the case the seals inside the axle will be questionable - but that cylinder currently isn't jamming so fingers crossed on that one

Unfortunately that wasn't all that arrived after lunch. We had a huge down pour, so work has stopped for the moment

vtsteam · « **Reply #52 on:** November 17, 2015, 09:02:03 AM »

Andrew, cool to see you on another project!

awemawson · « **Reply #53 on:** November 17, 2015, 09:35:37 AM »

Thanks Steve - I'm afraid that they are never ending

vtsteam · « **Reply #54 on:** November 17, 2015, 10:43:10 AM »

Good! (I don't mean that in a bad way.....)

awemawson · « **Reply #55 on:** November 18, 2015, 01:26:08 PM »

Bit of a frustrating day today

I did manage to fit the new Master Cylinder for the foot brake, but when I came to bleed it I couldn't for the life of me find my little red rubber bleed tube - you know the thing - thick walled pliable rubber with an aluminium rivet in one end and a fine slit. Other end goes on the nipple and the slit acts as a one way valve. I KNOW that I have one, but where - not used it in years - never mind - ordered up a new one - a long one this time so maybe I can watch it AND pump the pedal, as getting SWMBO involved in brake bleeding is a recipe for arguments !

So never mind - re-fitted the floor having first filled up the front axle casing, rear axle casing and transfer box with oil, and greased as many grease nipples as were accessible. (Some on the UJ joints on the prop shafts (there are three prop shafts!) were totally inaccessible with a grease gun )

Then I decided to fit a horn. This dumper never had one, not really for warning when driving, but when you are working with someone else driving a digger, often you need to attract their attention. I had a brand new horn left over from my JCB 803 re-furb, so I bought a rubber covered 'heavy duty starter button - rubber covered'. Well it does the job, but the aluminium alloy body is a horrid screw fit to it's brass mounting nut - some one in China has a tolerance issue

Managed to squeeze the horn under the mounting for the drivers seat, with the button on the panel that the ignition switch mounts on, as that was where I was picking up a live feed from.

I took it for a drive round the yard. Hairy experience with no foot brake, and dramatically better performance than previously - however I noticed that the steering ram that flexes the articulated steering is leaking. Not surprising - the end eyes are well worn, I have a line on one from a dumper being scrapped.

So - twiddle thumbs time till the tube arrives .......

edward · « **Reply #56 on:** November 18, 2015, 07:31:18 PM »

Could you get one of the gunson easi-bleed caps to fit the reservoir for the brake fluid? They are way better than the pedal pumping method if you can use them.

Manxmodder · « **Reply #57 on:** November 18, 2015, 09:40:17 PM »

I can watch it AND pump the pedal, as getting SWMBO involved in brake bleeding is a recipe for arguments ![/b][/u]

Oh yes,Andrew. I've been there a couple of times before now.

'I thought I said press down and hold it there until I say up again!

....OZ.

awemawson · « **Reply #58 on:** November 19, 2015, 06:34:11 AM »

We have Brakes

The postman kindly brought the replacement brake bleeding tube this morning, and as it hadn't started raining (forecast though) I set too.First job was to find a way, in the absence of a helper, to keep the brake pedal pressed and definitely not released, until I had re-tightened the bleed nipple on the axle. I found that I could rig up a large 'Carver' welding clamp between the chassis and the pedal, so then I could go ahead.

Probably worth pointing out that this brake system is not like the sort that you get on a car - it has two sets of oil immersed brake disks inside the axle, one either side of the differential. They are actuated by concentric cylinders and pistons, each with an 'in' and an 'out' port on top of the axle casing. Fluid from the Master Cylinder is routed to one 'in' port, the 'out' port of that cylinder is piped to the 'in' port of the second cylinder in rigid pipe, and that cylinder's 'out ' port has a bleed nipple in it.

The process its, slacken bleed nipple with tube attached, depress brake pedal and fix it down, tighten bleed nipple, release pedal slowly so master cylinder re-fills, then repeat the cycle.

As I was far from sure that this system had been filled with the correct mineral oil fluid that is compatible with the seals (Not one of the standard 'DOT' fluids), I wanted to flush out all the old, so it's good that the cylinders are in series rather than parallel.

Got it all set up, rubber tube on nipple, catch flask in place, then the rain started. Hang it carry on, just get wet

The old fluid was a very different colour from the new, so it was quite easy to see when we went from old, to mixture, to new just from the colour. Interestingly there must also be a marked difference in the viscosity, as, as soon as the new fluid started coming through, depressing the pedal became much easier forcing the fluid through the bleed nipple. Got through two complete reservoirs of fluid in the end.

As you can see from the picture, the old stuff was in a right mucky state. Smelling it I think it was a mineral oil, but not the right stuff. (I've been sniffing bottles of DOT3 DOT4 and DOT5 brake fluid, I hope nobody notices and gets me taken away

)

Pedal seems pretty solid (air in system gives a spongy pedal) and driving it back and forwards the length of my loading dock it works OK, but by this time it was pouring down and time to clean up.

Pete W. · « **Reply #59 on:** November 19, 2015, 06:53:21 AM »

Hi there, Andrew,

I've had three different Citroens that floated on LHM. When I was far from home and suffered an LHM leak on the first one, the RAC roadside rescue bloke told me that 'the book' says it's OK to use a light mineral oil if LHM isn't available. To be sure, the recommendation is to have the system flushed and refilled with LHM as soon as possible.

Maybe the previous owners of your dumper followed the first part of the routine but didn't bother with the second?

vtsteam · « **Reply #60 on:** November 19, 2015, 02:58:37 PM »

Oh man, yelling to the lady in the drivers seat "Now hold it down!" while lying upside down under the car with a wrench on the slave cylinder, opening it up and brake fluid squirting in your face, and dripping down your arm, and she in front letting off the brake before you got it screwed back on, sucking in the air........ those were the days!

Eventually I got so I could prop my heavy tool box on the brake pedal, scoot under the car, loosen and tighten the screw before the pedal hit the floor. Well before I discovered the tube in the jar method.

edward · « **Reply #61 on:** November 19, 2015, 07:08:33 PM »

I went through that pedal-wife-swearing cycle a few times and in the end I bought an easi-bleed kit which uses a reservoir pressurized using tyre pressure to drive the fluid through from the header - just open the bleed nipple, let the fluid flow and then shut it off when it flows clean or you have collected enough to be sure it has changed everything in the line. No danger of air sucked back in or anything.

All fine until you snap a heavily corroded nipple off in the cylinder. Much swearing ensued!

This is all on conventional cars though, the dumper seems to be a whle different kettle of fish:)

this one http://www.amazon.co.uk/Gunson-G4062F-G4062-Eezibleed-Kit/dp/B001KTFIWA/ref=sr_1_4?ie=UTF8&qid=1447978388&sr=8-4&keywords=brake+bleed+hose

awemawson · « **Reply #62 on:** November 20, 2015, 02:39:38 AM »

I agree about the Eezybleed , it was one of those I couldn't find. I can see it in my mind, tallish square cardboard box, predominantly yellow, with a plastic reservoir and various master cylinder caps, and of course the pliable rubber tube. Now I've done the job you can guarantee that it'll show up any day now.

The possible second hand steering ram turned out to be a different shape. I've bought a seal kit for the original ram, and assuming it dismantles ok I'll have to find a way to re-engineer the end eye to lose the gross wear. Maybe build up with weld and re-machine, or possibly cut off and weld on new.

edward · « **Reply #63 on:** November 20, 2015, 03:27:39 AM »

I feel your pain. Recently spent longer than the job should have taken looking for my oilfilter socket. Of course the blasted thing turned up in a different tool box the day after the replacement arrived!

awemawson · « **Reply #64 on:** November 24, 2015, 10:08:56 AM »

Time to attack the steering ram that articulates the front and rear of this dumper. It's leaking hydraulic oil quite badly, and it's spherical bearings (rod and cylinder) are badly worn.

I'd sourced a set of seals for it that are allegedly correct, but the supplier couldn't give me actual dimensions, there is no guarantee this cylinder is original so it was a bit of a chance if they fit.

So first whip it off having moved ram to closed position to expel as much oil as possible and identified the hoses and blanked them off.

awemawson · « **Reply #65 on:** November 24, 2015, 10:14:44 AM »

Then the moment of truth - dismantle the cylinder and compare new set of seals.

First remove the end cap - these frequently are horribly stuck, and I've been putting 'Plus-Gas' on the threads of this one for the last few days - it came out easily

Certainly the new seals do look to be correct

- it's a 1" rod and 2" bore cylinder - supplier could only say "about 50 mm on the outside" which isn't close enough in this case

The rod seal is probably the leaking one, but I'll change all of them

awemawson · « **Reply #66 on:** November 24, 2015, 10:21:28 AM »

Next the spherical bearings - they were HORRIBLE

They are welded on 'attachments' to the rod and cylinder with a 1" bore to the sphere itself, but I couldn't find any - only metric ones, and if I were to use those I would have to cut the mounting lugs off the dumper itself and make metric ones as well as 25 mm pins.

The eyes will need slicing off the rod and cylinder end whatever I use, for the replacements to be welded back.

I did however find a source of 1" 'spherical inserts' that have a parallel outside, so I'm going to turn up a housing for them and weld the housings to the cylinder and rod end. They are on order so a bit of delay in the proceedings.

I decided to make new pins anyway as the old are rather worn

awemawson · « **Reply #67 on:** November 24, 2015, 10:30:45 AM »

Now the pins are simple affairs! Just a 4" length of steel bar with a tab welded on one end for a locating bolt to stop it turning, and a co-axial hole up the lower end for a grease nipple, with a radial 3 mm hole for the grease to squirt out of into the spherical bearing.

I had some EN8 1" bar to hand but it could as well have been mild steel. So I set too making bits. First cut the components, then drill the various holes, then weld them up - how hard can it be

The shaping of the keeper plates was done free hand on the sanding table - shape isn't critical

awemawson · « **Reply #68 on:** November 24, 2015, 10:34:47 AM »

I decided to give them a light nickel plating to stop the rust. Can't be too heavy as it's easy to plate a pin so it no longer fits - ask me how I know

They were sand blasted and I didn't polish them before plating as the job doesn't warrant it. A quick 15 minutes in the plating tank and a trial fit

Spurry · « **Reply #69 on:** November 24, 2015, 12:59:58 PM »

Sorry to be dim, but what is that gadget in end-cap-removal.jpg photo. I've obviously lead a very sheltered life.

Pete

awemawson · « **Reply #70 on:** November 24, 2015, 01:04:32 PM »

It's an adjustable pin spanner - it is adjustable for spacing of the pins, and the pins themselves are interchangeable (I have a selection of different diameters

appletree · « **Reply #71 on:** November 24, 2015, 03:30:15 PM »

Quote from: awemawson on November 24, 2015, 01:04:32 PM

It's an adjustable pin spanner - it is adjustable for spacing of the pins, and the pins themselves are interchangeable (I have a selection of different diameters

Nice bit of kit, like me you appear to have lots of tools, abilities, and experience to carry out most tasks. Where did you gather all this?

awemawson · « **Reply #72 on:** November 24, 2015, 03:40:03 PM »

Question of necessity really - when thing's are broke, and you are broke, no one else is going to fix them for you

Spurry · « **Reply #73 on:** November 24, 2015, 06:00:18 PM »

Quote from: awemawson on November 24, 2015, 01:04:32 PM

It's an adjustable pin spanner - it is adjustable for spacing of the pins, and the pins themselves are interchangeable (I have a selection of different diameters

Thanks Andrew. I've never seen one of that type before. I guess it would remove very heavy circlips too.

Pete

awemawson · « **Reply #74 on:** November 25, 2015, 10:18:38 AM »

A bit of progress today - the spherical bearings arrived, but not the circlips to retain them.

I made a start on the housings for the bearings - I had a bit of unknown origin 2 3/4" bar that seemed a likely candidate as the original housings are 2 1/2.

Faced it off and reduced the outside to 2 1/2" then drilled it 1 5/16" - it needs boring out accurately to 1 5/8" but I will leave it over night chucked up to return to room temperature.

Looking at the way it turned, I suspect that this bar is a bit more than just mild steel, a good thing for strength just so long as it welds ok.

...why drill to 1 5/16" ? Well it's the largest drill I have on a 3 MT shank and to use a nearer one to finished sized I'd have to use a 'jump up sleeve' to 4 MT and although I have one, the whole caboosh gets very unwieldy.

I need to grind an internal grooving bit to make the circlip grooves, but can't do that yet as I need to measure them first.

News:

Author Topic: Thwaites 2 Ton Two Cylinder Dumper Running On One Cylinder (Read 138512 times)