7mm 'Denton Brook' an industrial whimsey

[Giles]

The current slew ring has to go, and the external gear must replace it. It used to be a full gear I saved from something twenty years ago (can't remember what) and I cut the centre out with a piercing saw to take the thin profile bearing, which was bedded I with Milliput (the loads of course being minute in real terms). Care was taken to get it as concentric as possible, however, to avoid the minor gear from disengaging.





One fiddly job, however was the minor gear was cored with a 'D' hole the wrong size. This needed boring out round, and then bushing ready for the slew motor. In order to hold this in the lathe, a piece of tube was cut and used as a 'split collet' to protect the teeth and hold it concentric. This job went fine, and a brass bush was araldited in.

 

[Giles]

The slew gear was araldited to the cleaned-off foot plate, And then a top plate with female part to sleeve the bearing internally was made. This was a short piece of 15mm copper water pipe, just thinned down a fraction to fit the bearing, silver soldered to a brass plate which will nest to the underside of the crane cab, and then a hole made again to take the slip rings.






Top plate is then araldited into the bearing






The crane base in position on the top plate showing what's what.

 

[Giles]

The motors within the crane are all of the 6v gearmotors type. The slew motor is 14rpm, and the two winches are 30rpm (rated) both actually will be working on 3.7volts, of course

This is the slew motor in position



And the winch assembly (Derrick on the bottom, and hoist above)

 

[Giles]

Winches fitted, now with drums (10mm X 10mm - turned from brass stock).

They butt right up to the cab side in order to get the drums central enough - but it's ok. It's also an extremely tight squeeze in the other dimensions. I could have cut away the internal pillars, but actually they're in the ideal place, underneath the pulley shaft - so I really wanted to make the positioning work - and it does!

 

[Giles]

The crane part is complete and working, but I really wanted to power at least one set of stabiliser jacks. This was really not easy, as there is very little pace to do anything. However, after quite a lot of thinking, I cut off the original rear jacks, and made an entirely new set - matching, but with a slightly deeper housing ( dropping closer to the ground) and 3mm further to the reaffirmed the vehicle.



The mechanics are entirely inside the sandwich of the main plates, except for the servo, which is between the chassis rails, and not really in view. The larger gear in the centre cluster is a temporary one and is where the servo with gear is located.
This whole assembly is laser cut, and each gear is three laminations thick, with shafts of 1.5mm silver steel.

 

[adrian]

The mechanics are entirely inside the sandwich of the main plates, except for the servo, which is between the chassis rails, and not really in view. The larger gear in the centre cluster is a temporary one and is where the servo with gear is located.
This whole assembly is laser cut, and each gear is three laminations thick, with shafts of 1.5mm silver steel.

Brilliant to see how you've crammed everything in. Just a few questions if I may. The laser cut gears, what material have you used? Is it trotec (?) like the miniature nuts? Also why 3 laminations? Was it just the material you had in stock or is it a limitation of the laser cutter?

Finally for the vehicle itself is it going to be static or mobile? Looking at the last photo with bearings in the main wheels I suspect the latter.

 

[Jordan]

Sometimes "awesome" is an over-used word.

This time I think it's rather inadequate, in fact....

 

[Giles]

Brilliant to see how you've crammed everything in. Just a few questions if I may. The laser cut gears, what material have you used? Is it trotec (?) like the miniature nuts? Also why 3 laminations? Was it just the material you had in stock or is it a limitation of the laser cutter?

Finally for the vehicle itself is it going to be static or mobile? Looking at the last photo with bearings in the main wheels I suspect the latter.

It is a touch tight....!
The gears are indeed Trotec - they're 3 laminations so that they're the same thickness as the outriggers, which match the front ones, and have a slight recess in the the centre to take the screw jack. This is all 0.8 stock. I do have 1mm, but I don't have any trotec thicker than that (I would only use it very occasionally). It's very easy to laminate up, so it's no problem.

The Trotec is quite a nice material, and certainly for slow speed gears it's fine. Whether it would be any use for high speed gears I don't know.

The vehicle will indeed be fully mobile, and the crane is also fitted with slip rings, so it twizzles round and round endlessly, without getting its wires in a twist. The truck drive motor is already in place, with its simple bevel gears to the rear axle, so mechanically, I've just got the front steering axle to do.

 

[Giles]

Throughout all, I've been gently progressing Denton Brook, (apart from the very front, which I'll do last so it doesn't get damaged) and I've got the bulk of it very nearly ready for grass....








I'm still in several minds as to what I shall be doing with fiddle yards, including whether to have a 'road fiddle' at the open end or whether to bring lorries in along Tram Road.... Certainly to begin with, rail wise there will only be one fiddle at the factory end. Operating this little lot is a little unknown as to how it will pan out in practice, what with two gauges of railways, road, and two cranes.....

 

[Giles]

This is a reverse shot if the outriggers, showing the servo and the rear axle drive. ...(simple)

 

[Giles]

The front wheels each require a (handed) stub axle/king pin assembly. This just happens to be a little block of steel, cross drilled for the silver steel axle, then drilled again for the (1mm mig wire) King pin. A NS steering arm was then silver soldered on. It's important to get the whole lot, with the king pin as far into the wheel as possible, to prevent the wheel 'tracking' backwards and forwards as it steers.



The assembled axle, which shows the relative positions.



Still the centre pivot to go on.

And with the pivot

 

[Giles]

The front axle mounted. The track rod has that strange V in it for adjustment - you can open or close it to alter the tracking...

Note they eye to one side to take the drag link as soon as the servo is mounted.

I dislike making steering axles, as they're all different for different vehicles, as no mountings are the same, and they're always a fiddle - but this one's been reasonably straight forward.

 

[Osgood]

Fantastic stuff!
Remind me again please - for the rear axle you drive only one wheel to avoid the need for a differential and to avoid wheel scrub?

 

[Giles]

Ah, no - my very first experimental was doing that, because I assumed the scrub would be excessive and cause cornering problems- but in practice, that proved not to be a problem at all, and a fixed axle was preferable and performed much better. Since then, I've not bothered, and simply driven a simple shaft between the two wheels!

 

[Jordan]

..... - but this one's been reasonably straight forward.

Obviously this is a new definition of the phrase "reasonably straight forward" that I was previously unaware of....

 

[adrian]

The front wheels each require a (handed) stub axle/king pin assembly.

Again very impressive. What stops the front wheels falling off? Do you just loctite the bearing to the stub axle or do you have some other cunning mechanism?

 

[Giles]

A spot of araldite does the job - nothing sophisticated on this....

 

[Simon Glidewell]

Thundering typhoons!!! The work of a genius...

Fab stuff Giles!

 

[Giles]

The stabiliser servo failed, so I've had to have the back end off and replace it with a slightly bigger servo - I've just got to remount them.....

 

[Giles]

The Crane basically complete, before the back end transplant, and with body loosely placed!