WW1 Thornycroft restoration

[Minesweeper]

Just come back from a few days away to read these last few postings - and I think that all the questions have been beautifully answered! With the small hole - just 1/8" in diameter - then a rivet will be inserted through the two opposing holes (on each side of the leather) to keep them in place - but the rivet will simply be a bit of 1/8" mild steel rod with the ends riveted over! Barry's pictures illustrated this method very well! Tony

[Chaindrive]

I have had a look at the clutch setup on the part Thornycroft engine that I have (page 81,post 809). Looking at the remains of what is left,it is not leather,but looks like the material used on the Dennis pictures on the previous page. What is interesting however,is that in this case 4 rivets have been used,not 3 as in the Dennis. Does this then make the Thorny better than the Dennis!!!? I would imagine that it would have originally have used leather material which was replaced at some stage during its working life.

 

 

 

 

[Richard Farrant]

Hi Chaindrive,

That coupling looks like it was made of rubberised canvas.

 

regards, Richard

[mattinker]

Hi Chaindrive,

That coupling looks like it was made of rubberised canvas.

 

regards, Richard

 

I would go so far as to say the look like they've been made of old cotton reinforced tyres!

 

Regards, Matthew.

[Asciidv]

What is interesting however,is that in this case 4 rivets have been used,not 3 as in the Dennis. Does this then make the Thorny better than the Dennis!!!?

 

 

 

Well, that is a difficult question to answer.

 

Perhaps it was the fourth unnecessary rivet that drove Thornycroft into decline due to the extra expense. Two weeks ago I was at a Dennis Factory open day, where you could see steel entering one end and complete bus chassis leaving the other end. There were no Fire Engines on the lines (and never will be anymore) but at least they are still manufacturing despite Steve having left them several years ago!

 

Barry

[N.O.S.]

The 4 rivets, shape of plate and type of fabric are indicative of a later type of Hardy designed coupling, many of which we used in conveyor and other drives. They were the cheapest and most common style of flexible drive coupling (usually with cast iron disc type coupling halves having 3 holes and 3 slots in each), and were available from most of the power transmission product manufacturers - Fenner, Croft etc, most of which have now gone. Have not bought one since the early 90s, but they may still be available?

 

However here is a company making new couplings from the original Hardy tooling - may be useful:

 

http://www.gmspolymer.co.uk/flexible-couplings.htm

 

(Well, you could spend a lifetime trawling through skips and never find a sheet of pump leather. :cool2: )

Edited June 25, 2013 by N.O.S.

[GeePig]

Do the rivets for the rubbery versions also act as spacers?

[flandersflyer]

The way I see it is the shaped washers are backing strengtheners for the holes drilled in the leather, which acts the same as a modern rubber coupling, simelar to a Hardy Splicer unit! The centre hole does nothing except look pretty...! (as with everything else on this vehicle!!!):cool2:

think triumph rotoflex

 

[nz2]

Aside from leather being used for these yokes, I have seen industrial conveyor belting fitted. Being a laminated structure the belting would with stand the forces imposed on it.

There does also appear to be slight changes in the cast parts of the flexible joints over the period of time of Thornycroft J production.

Doug

[Great War truck]

Since the worm straightening exercise, Steve has assembled the steering box. It was quite straight-forward. The original radial bearings were re-fitted followed by the new thrust bearings.

 

 

 

 

Then the slotted discs were installed followed by the shaft assembly before dropping the whole lot into one half of the box.

 

 

 

 

A handfull of grease was added and the other box half was fitted. The bolts were knocked through and the nuts nipped up finger tight before fitting the end-float adjuster plug.

 

 

 

 

As we have discussed before, the adjuster plug is secured with a ring of piano wire which has the end bent over. This, in turn, slots into a radial hole through the case and into the plug. You can just see the hole at the top of the picture.

 

 

Of course, our new thrust bearings are a very slightly different thickness so the radial holes no longer line up. For the time being, the plug has been adjusted up without drilling a new hole as we plan to do this when we assemble the whole steering column and mechanism. The main casing bolts have tightened onto the plug so hard that it cannot be moved by hand anyway. Finally, the base was added. The box has now been put away until we are ready to start on the missing column.

 

[Stormin]

No gasket or sealant between the two case halves? How is this going to remain oil tight?

A paper gasket may make all the difference to how tight the end float adjusting nut is too.

[Richard Farrant]

No gasket or sealant between the two case halves? How is this going to remain oil tight?

A paper gasket may make all the difference to how tight the end float adjusting nut is too.

 

I would say as it would have had a heavy grease used in it, not like the oily stuff we have today, there would be no gasket. The two halves would have been machined together to accept the bearings and screwed end plug. Any gasket would not allow the casings to pinch the bearings and also effect the screw thread. That's my thought anyway

[Minesweeper]

I would say as it would have had a heavy grease used in it, not like the oily stuff we have today, there would be no gasket. The two halves would have been machined together to accept the bearings and screwed end plug. Any gasket would not allow the casings to pinch the bearings and also effect the screw thread. That's my thought anyway

I think that you have it exactly right, Richard!

Tony

[Barney]

During my apprenticeship there was an old boy, Fred, in the garage who would only ever use Duco Goldsize on metal to metal joints and on copper asbestos head gaskets. I never saw joint that he had made fail. Fred had a hatred of Red Hermetite, Sunday mechanics jam as he used to call it. I initially wondered why until I had to scrape a whole tube of the stuff off an Austin Mini timing cover and engine front plate after the owners botched oil seal replacement.

Best regards. John

[Great War truck]

After Adrian’s successful leak treatment, Steve applied a bit of filler to the water pump inlet casting just to hide the welds. He then clamped the casting to the cross-slide on his lathe and drilled out the screws which had secured the brass instruction plate. These were re-tapped at 1/8” Whitworth.

 

 

 

As he didn’t have any screws of this size in stock, he turned some up and slotted them in the mill before trying them out.

 

 

 

[Great War truck]

He then passed the job onto Dad who made up a gland follower and a new bronze bearing. As the casting is so thin in the area of the bearing, Dad secured it with Loctite rather than risking pressing it home and cracking the casting. He then undertook a trial assembly .

 

 

 

 

 

 

 

Then, he painted the castings and, after making up a new gasket, put them all together again.

 

 

 

 

 

All that remains of this assembly now is to make up a new ‘onion’ support casting to replace the heavily corroded original. Steve will be starting on the pattern shortly.

[Minesweeper]

Should anybody be wondering about what has happened to the Piston castings, then they are still with our friend Andy W to have the holes bored in them for the Gudgeon pins. Andy works commercially and has been up to his eyes with his bread and butter work and has just not had time to do the job - so that is delaying the final work to be done here on them.

[N.O.S.]

There has to be a reason why the impeller retaining pin (is it tapered?) is so long, but you'll need to explain please!

 

Surely not for breaking ice....:cool2:

[Minesweeper]

There has to be a reason why the impeller retaining pin (is it tapered?) is so long, but you'll need to explain please!

 

Surely not for breaking ice....:cool2:

 

No! It is just a standard taper pin that we had in stock - it will be shortened on final assembly!

[Great War truck]

Steve has been pressing on with preparations to machine the pistons as soon as they come back. To that end, he has made the draw bar and cross-head to pull the pistons back onto the face plate. He has also faced and drilled the mounting plate ready to bolt it to the face plate.

 

 

 

Steve wondered where he was going to get hold of a big chunk of aluminium of steel so he asked Adrian.

 

‘What about this?’ said Adrian producing a 10” disc of 1 1/2” plate from the back of the car. He must be a mind reader! Thanks Adrian!

 

Steve has also been putting together some chunks of MDF to make the pattern for the ‘onion’ casting. He can’t turn these at home but they are ready for when next he goes down to Devon and can use the Colchester. He used the press to hold the bits together as he doesn’t have any G-clamps big enough!

 

 

[Barney]

Steve

I was wondering how you intended to build the pattern.

Do you intend to cast a whole hollow onion and then cut the side out or make a more complex pattern to include the cut out (thought; is this possible)? Can you see how the original onion was made?

John

[Asciidv]

This is going to be interesting!

Are you going to cast the core box from something like plaster of Paris?

 

Barry.

[Old Bill]

You've stolen my thunder Barry! Yes, that is part of the plan.

 

My intention, at the moment, is that the right hand lump will be turned to the outside dimensions of the onion with the big core print at the bottom and the little one at the top. The centre lump will be turned to the inside dimensions to become the shape of the core. The left hand lump is to be turned to the outside dimensions of the main pattern in the area of the hole. This, I plan to cut to the profile of the hole and glue to the core block giving a section, raised by about 1/4", in the area of the hole. That will support the core in the hole in the sand.

 

Now, the clever bit. I shall make up two core boxes as empty wooden boxes. The wooden core will be supported half into the box and the box filled with resin around it. It will then be reversed and the same done for the other side. This should give me two core boxes, one for each half of the core. The moulder can glue the core halves together before placing them in the mould.

 

Well, that's the theory anyway. I have not done this before but will keep you posted with progress!

 

Steve

[flandersflyer]

He then passed the job onto Dad who made up a gland follower and a new bronze bearing. As the casting is so thin in the area of the bearing, Dad secured it with Loctite rather than risking pressing it home and cracking the casting. He then undertook a trial assembly .

 

 

 

 

 

 

 

Then, he painted the castings and, after making up a new gasket, put them all together again.

 

 

 

 

 

All that remains of this assembly now is to make up a new ‘onion’ support casting to replace the heavily corroded original. Steve will be starting on the pattern shortly.

outstanding....

[flandersflyer]

and here`s a lesson to all...never assume something is dead...

it can nearly always be brought back....