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Radio controlled road vehicles on Upper Benllech


otherplanet
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Just to show I can do 'railways' and not just roads.

I recently completed this little set for the planned layout.

DSC_4171.JPG.bc316c2626bbb333b61ddaa629f34513.JPG

 

This isnt entirely off topic.

The wagons are to enable development of road to rail transfer. 

The concept for the layout is the "goods in" area of a housing construction site. Served by an internal contractors railway. 

Something I have seen in a number of pictures, most significantly Selsdon where I grew up and Letchworth garden city. Which between them are providing the inspiration. 

For this to achieve the operation I require. I need to unload from road vehicles to storage bays and directly to the wagons. Hence needing some wagons. 

The next stage is a side tipping trailer. I am trying to replicate a mechanism used in pre hydraulic tipping vehicles. The trailer bed is winched sideways until the centre of gravity gets far enough off centre and the load tips downwards.

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The idea is to use a set of infra red transmitter and reciever to transmit a servo signal from the main vehicle. I have a motor drive pcb which will then convert this signal to motor speed rather than servo position. When the signal is disconnected, it stays at the last setting until the signal is re established. (servos work the same way)

 

The wagons will be helping test this tipper and define key geometries of the layout.

 

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  • 2 months later...

Progress has been slow but steady, but the results have not been very photogenic, with the details not really being visible. But its now starting to come together.

768969138_bodyinwhite.png.5afb0e27a63bd073fafe0c42ee54b308.png

I have focused on the tipping mechanism before worrying about the wheels and undercarriage. The body is built from plastikard, there is still lots of detailing like strapping etc to add. The tipper body features a set of transverse L section rails, which in turn rest on beams that form part of the lower chassis.

Underneath, a windlass hauls the body sideways until gravity causes it to tip. Stay chains at each corner restrain the movement.

 519655920_baretippermech.png.f8e28372947ddf07fb6a9ac47d071aca.png

On the prototype, the windlass would be wound by the driver (or his mate) using a 3ft long ratchet wrench. On the model I am using a 4mm planetary gear motor from sol-expert. It has to fit between the frames, which is very limited space, so I had to dismantle the gearbox, which is modular and separates into 3 rings, each with an epicyclic gear-set inside. So I reduced these from 3 down to 2. (125:1 reduced to 25:1) and swapped the motor for a shorter 4mm motor.  

1875689090_gearboxstack.png.b00f5f8dcd3c02e673caaadd27527efb.png

The standard motor gearbox is held together by a tube of heat shrink. Having modified the contents, I re-assembled them into a pair of brass tubes to keep everything rigid and concentric. Everything except the output gear is 4mm diameter.

815538285_assembledmotor.png.1bb602ceb4841e71cd141a191bb508f2.png

These then fit into one end of the chassis, driving the windlass via parallel worm gear.

 underneath.png.50118438c885d9032c67b2e7d34e51b0.png

At the opposite end, there is a pair of latches, these hold the 'top hinged' doors closed. The weight of the body resting on the slide rails of the chassis keeps the latches closed until the body is winched off centre. These work nicely now, I am hoping these will still release when there is a load inside pushing against the doors.

 

The control system is still under development, the motor is driven by a bi directional ESC which uses the servo signal from the tow vehicle's receiver. An Infra Red LED is connected to the RC receiver and was intended to control the ESC via a photo-diode. However, the best range I could achieve was 5mm between LED and photo-diode. Which is not enough to be useful, so I now have now ordered some phototransistors to hopefully increase the sensitivity. However, the basic principle did work, the motor could be controlled smoothly with an air gap between the 2 vehicles and it coped with them being moved out of range, without the motor running away due to lack of signal.

So far all the above has been tested independently, but next needs to be fully assembled and tested. If it works, I can then take it apart to start painting and build the running gear, turntable, etc.

This last picture shows the new wagon (without doors) alongside my existing wagon for the Atkinson for perspective.

2021483741_withatkinsontrailer.png.dced5204ec298a3906c02b1d00160b49.png

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  • 6 months later...

Well its been a while. 

Shortly after the last post, I had to pack up all the modelling equipment, along with the rest of my study so that it could be knocked down as the first stage of some building work. With everything boxed and scattered between our house and my parents garage, I resorted to armchair modelling, something I am far too inclined to indulge in anyway.

Then, with the foundation poured, we went into lockdown.

Consequently nothing has happened on the trailer.

But armchair modelling led to considering ideas for a K&ESR layout, which lead to thoughts of what time period to choose, which lead to investigations of what road vehicles might be available for conversion to suit those time periods.

The Merit Thornycroft PB lorry, proved difficult to find much historical information or pictures until I found this website.

http://www.archive-images.co.uk/index.search.php?cmd=doSearch&new=1&keywords_simple_boolean=gwr+lorry

I had always thought the body to look rather odd in the kit, but these pictures made it all make sense. It also stimulated a need to order one immediately. Along with the various other bits needed to replace what was stored in a garage a lockdown away.

 

Its been a slow build, but with lockdown eased, my wife and children went to visit her mum for the weekend and I got 2 days of dedicated time to make progress. so I now have the chassis running, not finished, but running.

 

The oversized battery is just for running in, the final one will fit in the bed. 

The motor sits just infront of the rear axle and is standard 6mm gear motor, but I ordered from a different supplier to get one with a long shaft, the worm glues straight on with no need to extend the shaft. There was even enough spare length to add a brass bearing on the end.

The front axle is cut from 2 layers of plastic sheet and uses a slot cut through the front springs as hornblocks to keep it controlled, it pivots on a piece of steel wire passed through the crankcase which is also slotted. 

The steering knuckles are made from U section channel. These were cut to create the track rod arms and drilled for the kingpins, plus a hole for the 1mm stub axle. The right hand knuckle also has a second piece of channel for the crank to the servo 

IMG_20200726_144819_6-01.jpeg.dee78092ce1bfe3ad8cb708e12857c84.jpeg

I used channel from Chronos, as the wall thickness is larger than most. the limited clearance to the chassis frames meant the throw had to be  quite short. The linking rods are formed from 0.5mm steel wire, rather than bending into a hook, they are bent to 90 with a tiny piece of 0.1mm wall thickness tube, also from Chronos. combined with the drilled holes, this has resulted in a steering mechanism which has much less freeplay than my previous attempts. Which valuable given the complications needed with the servo, see below.

The wheel bearing uses a Romford top hat bearing, held in place by a very short piece of tube, on the end. The top hat then gets glued into the wheel, very carefully! 

IMG_20200728_220616_8-01.jpeg.0307244853531167a6df4801d165865e.jpeg

The servo, sits flat in the cab, I trialled various ideas, but struggled to find a good orientation. The need to keep the travel short meant that a simple crank arm, passing through the floor, meant that the only about 30% of the servo throw would be used. 

The final solution was to drill a hole into the spigot of the servo, insert a pin, and then an rocker arm links from the servo, through a snug hole in a brass plate glued to the floor, this shortens the throw, makes the movement more linear, but unfortunately reverses the travel, which was solved by rewiring the servo motor and potentiometer.

 

The headlights and driving lights were drilled out and fitted with surface mount warm white LED's and the lenses made using UV cure resin from greenstuff. This works really well and I have used it to pot the wiring in places to keep things secure.

The headlights have a 4K7 resistor and the driving lights a 10K, this makes them a little brighter than the those on the Prewar vehicles.

 

I have used the Deltang RX47 receiver, which is nicely laid out, and slightly narrower than the others, and therefore fits nicely between the chassis frames between the motor and cab. I think I will need to get a couple of spares of these before Deltang run out of stock. The only weakness is the +ve and -ve terminals are very close together, which I feel is a little risky.

 

I have added two tool boxes on either side of the chassis to mount the power switch and charging socket. 
This is not present on the GWR versions in the historic photo. But the Thornycroft website has pictures of a demonstrator model (normal flat bed) which has these boxes, so I feel a little modelling license is reasonable. 

https://www.thornycroft.org.uk/Thornycroft Group C.htm

 

I still need to finish the chassis details including things like the wheel arches. Then I can move onto the truck bed. 

Obviously the objective will be to try and get this to operate. I have a second long shaft motor with a lower ratio which I intend to use as a winch. This and the final battery will go into the fixed part of the body.

 

Oh, and the extension building is now finished externally, so soon, modelling will get interrupted again so I can focus on fitting out the new modelling room.

 

 

 

 

 

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  • 8 months later...

After a 5  different attempts, the mechanism finally works satisfactorily. It's not as small as I wanted and the tilt doesn't slide as smoothly as I had hoped. (A little more fettling still to go) but it now works and is ready to integrate into the chassis.

 

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Thanks. The original plan was to use the sliding of the tilt to operate the tail gate at the end of its travel. With a pair of tensioners on the fishing line, which would trip contacts to the end stop detect of the Rx 47. But the subtleties of making it work was too much. So there is one tensioner and the MK1 eyeball as the endstop limit.

It leaves enough space to cover the gubbins with a partial load and still have room to load and unload a large crate or box or two.

The tail gate deliberately drops under gravity rather than being pulled down (one of the things that proved harder than expected to get right) so that it can be dropped onto the surface of a loading bay, without lifting the whole vehicle into the air.

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  • 1 month later...

Finished at last, give or take some number plates and some plastidip on the front wheels to increase their grip for steering.

IMG_20210704_123748_7-01.jpeg.cccccaccd3e1efa07791626694455a00.jpeg

I am not perfectly happy with the smoothness of operation of the tilt and tailgate, but they will do. I have enabled the servo slow function on the tailgate to make the operation less of a crash, and used the max speed function of the RX47 to limit the speed of the tilt, which only has an on-off-on rocker switch to control it.

IMG_20210704_123526_3-01.jpeg.e902e192c7ba9d3b21edf95345702f13.jpeg

 

Since I have the decals from the kit, I have been able to finish this one and give it a little light weathering. On any layout I have planned from my armchair, this vehicle would be no more than a year or two old, (and that's the late era concepts). So I have assumed it is new, well looked after and therefore just some light road grime from the day deliveries, plus a bit in those hard to reach areas line the roof.

IMG_20210704_123226_1-01.jpeg.9343505de3fa306c5c20e7c086147d3e.jpeg

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Looked pretty smooth operation to me, I have to say. I thought the lorry movement was a bit abrupt, could do with slowing down more gradually. Just imagine those tiny little 1950s brake drums struggling to make themselves felt...

super work anyway.

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3 hours ago, StephenF said:

Looked pretty smooth operation to me, I have to say. I thought the lorry movement was a bit abrupt, could do with slowing down more gradually. Just imagine those tiny little 195020s brake drums struggling to make themselves felt...

super work anyway.

Corrected. Mind you solid tyred vehicles were limited by law to 12mph but most lorry's (and many cars) of the period had rear wheel brakes only.

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You are quite right, far too harsh a stop. Mainly due to the ham fisted, out of practise skills of the driver. Although it is capable of quite slow speed driving, the throttle is very sensitive. This has improved a bit since I took the video as a result of applying the Giles Favell trick of adjusting the PWM (although the RX47 doesn't get as low as 60Hz). Plus applying the "max speed" function to spread the available speed range across a wider percentage of the stick travel.

Incidentally. I measured it last night at the top speed is a scale 12mph. The prototype would have been capable of about twice that. I think the rules on top speed were increased about the mid 20s. (But haven't double checked.) Assuming you were on rubber tyres and within certain axle load limits.

 

You are also right, the brakes on the prototype were rear wheel only. The big drums are represented quite well in the kit.

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I also need to take up Giles' suggestion of upgrading my transmitter to  something with more sensitivity and adjustment, whilst I dislike the idea of the transmitter being 4 times the size of the vehicle. I have to accept that my home made single stick units do not have sufficient sensitivity to get the best out of these vehicle.

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Recommend the Orange TX6 or TX10 for around £80/£90.

 

The adjustments possible on the channels are extremely useful for fine-tuning the speed of motors that do (for example) ramps at the rear of my beavertail truck. These can be operated at 10-15% of full speed just by adjusting a menu on the transmitter, allowing you to get exactly the speed you want. You can also flip channels if you wire the motor up wrong and it goes backwards, or if you have to install the servo backwards and it goes left instead of right :) 

 

Also, you definitely need a hoist at high level on the warehouse to lift something on/off the lorry.

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7 hours ago, Pikey said:

Recommend the Orange TX6 or TX10 for around £80/£90.

 

The adjustments possible on the channels are extremely useful for fine-tuning the speed of motors that do (for example) ........

Thank you for the thoughts, I shall have to look into the options at some point soon.

8 hours ago, Pikey said:

Also, you definitely need a hoist at high level on the warehouse to lift something on/off the lorry.

I completely agree, I have an aspiration for a free standing yard crane. Although the temptation to knock up a building with an I girder crane out the door is very strong.

 

In the mean time I took delivery of some large 6ft X 3ft crates to put in the back. 

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  • 3 months later...

quote: '...upgrading my transmitter to something with more sensitivity and adjustment, whilst I dislike the idea of the transmitter being 4 times the size of the vehicle...'

 

Your remarks reminded me of a thread in a German forum  >>  http://www.mikromodellbau-forum.de/t3930f5-D-Druck-Frontlader-Unimog-Sender.html

 

- don't panic 'Google Translate' is your friend, 'DeepL' is even better -

 

There is a description of an Unimog with a self built transmitter using a Deltang Tx2. The instructions are pretty much self-explaining and on page 4 post #49 there is a full description of how to build a '2-gear system' making the throttle into a much more sensitve one.

 

For a genius like you it should not be difficult to design a case for the transmitter yourself!

 

And the size:

 

unimog.jpg.3807d1fd9fa67654c5819c5a44b3829f.jpg

 

Best, Eduard

 

 

Edited by 19Ted54
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  • 3 weeks later...

Yes, very much like that. A very nice piece of work, well done.

Unfortunately most of the 4mm scale cranes do not have the gears so well cast, in fact many have them cast in situ. And I won't have the space to mount the motor above the base board like that, so I think the challenge will be harder. I also only need a relatively light weight 1 to 2 ton capacity for the prototype.

I am quite tempted to go for a  wooden framed crane with a full height vertical post and the big windlass wheel at the top that is operated via a chain. I am thinking that could give me a route to put the motor in the base and hide a spindle up through the post to drive the cable spool at the top.

Not fully planned it all through yet though. May well change it by the time I actually attempt to build something.

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  • 1 month later...

Its been a while, much building & decorating work, along with family etc have kept me quiet.
But with the painting all done by Christmas I was finally able to justify treating myself to a 3D printer in the black friday sale.

Its a Phrozen Sonic Mini 4K, DLP resin printer


I have been working on the CAD for my first model over the holiday. 

 

This is intended to be the main vehicle(s) for a new layout and is the first RC vehicle built from scratch for me. (if CAD modelling and then printing counts as scratch building). I expect to need multiple to allow 1 in operation, 1 charging and 1 spare, as a bare minimum.

However I have started with a functional prototype, I have only focused on functional detail: how thin, how small, how strong, do they fit. Basically all trying out the capabilities of the printer, and teaching myself how to use it. A process which is definitely still in progress as I didnt manage to get all the supports in the right place and havent yet got the measure of the amount of swelling I need to compensate for when parts need to fit together.
Its also just the chassis and wheels

 

Anyway. here it is.

581519431_IMG_20220109_211031_5(2).jpg.6aeba661af5d27b0bd3ec3c37274394f.jpg

A somewhat unusual method of compensation for the front wheels, an attempt to avoid the need for pivot point in the middle.

940761266_IMG_20220109_211604_7(2).jpg.22ab1903a89ee676d7508a2e4cb9528e.jpg

536057201_IMG_20220109_212132_2(2).jpg.53578267dbc69814ba4586679ad54315.jpg

 

I am pleased so far.
there are a few bits which need beefing up, but mostly its much stronger than I had hoped.
Its printed much finer detail that I had hoped and finer features than I had hoped. Those leaf springs are only 200um thick.
So a few improvements, and then I can get on with some of the body and putting in more detail.
Dont hold your breath, printing is quick but my modelling is still slow.

 

Any guesses as to the prototype?

IMG_20220109_211826_7 (2).jpg

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  • 2 weeks later...

Next installment, this bit should help to identify the prototype to anyone who knows what they are.

782878419_IMG_20220120_213319_1(2).jpg.959e3c60b975c7391ba9f04bb6da8a3a.jpg
This is a Stronach Dutton patent tractor, made by Guy Motors for the RoadRails company.

It was invented to overcome the theoretical limitation of light railways that the weight of the locomotive needed to haul heavy loads resulted in the track needing to be made heavier and therefore more expensive than required for the wagons themselves. additionally, that the earthworks involved in minimising gradients also added to the cost. 
The tractors use the rail bogie at the front to steer and guide the vehicle along the line, whilst the big rubber tyres on the rear provide the traction with high grip to the ground. Additionally, the vehicle can demount from the bogie using a set of ramps, and drive off on the road, hauling a normal road wagon.
1829090049_IMG_20220120_213358_2(2).jpg.9dca50b418be0bec76ad4ba121273941.jpg
Whilst an oddity, I do not claim novelty on this model, there has been a very good website 
http://dave-mills.yolasite.com/stronach-dutton-road-rail.php

 

and a book by R.G. Cash from which I have taken a lot of inspiration.

 

There is also a video on the BFI
https://player.bfi.org.uk/free/film/watch-the-stronach-dutton-road-rail-tractor-1925-online

all of which are reference previously in RM web.

There have also been a few models, including a representation of the principle on 'Ankh Lesspork' (I think I have that right)

 

I haven't however seen any attempts to make a model of these particular vehicles. please tell me if you know different.

Obviously, the big opportunity for me, and the reason I have put this in the radio control section, is that I am planning to model this with radio control, so that I can run them both on the rails and on the road, (and hopefully demount them in between).
668527878_IMG_20220120_213430_2(2).jpg.3318d95fc0270d46c71acae470938029.jpg
The plan is to put a servo in the large box on the far side, on the near side there is a hinged lid which will secure the gear motor, which then drives through a couple of spur gears to the central drive shaft which runs to the top of the prototypically HUGE differential case.
There should be space above the motor for a battery and the receiver. and behind all of these on the platform above the driving wheels there is enough space for a second servo, which will hopefully operate and uncoupling mechanism for both the road trailer and, using a magnet similar to the unimog shared by Eduard above, hopefully the railway wagon tow bar.1078339967_IMG_20220120_213529_4(2).jpg.b4c022c3994e66e4b1f68123b6667965.jpg

 

Next step is to update the bogie design based on this first build and then model the cab and bodywork, at least the basic shapes. Meanwhile I need to order the gears so I can get it running.

 

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Yes. 4mm.

Thank you.

I did consider going up to 7mm, but decided it is possible to get everything in, and it will reduce the layout size and hopefully reduce the time needed to build a layout. Assuming I can get it to work.

 

I may yet regret that decision.

 

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