Driving Trucks

[Sub MandrelParticipant @submandrel]

Basic dimensions

[Sub MandrelParticipant @submandrel]

Hi folks,

A few quick questions about driving trucks… I'm planning a 5" gauge truck for elevated track. I have Alan Bibby's article in ME4002, but it doesn't give a lot of detail. Here are my questions and my guesses at answers…

Will 2 1/4" diameter wheels be OK or are they going to be too small (I will be using 3/8" thick rubber pads for suspension) – my guess OK but expect a rattly ride.

How long should a truck be to carry two people, or better – how short can I get away with? 30"?

How wide should I allow to make sure I don't foul the track on either side? 9", 10" or 12"?

How far below the seat level should footrests be? I'm guessing 12"?

How wide should the seat be? 10" or 12"?

How important are brakes if not used for passenger hauling?

Thanks in anticipation,

Neil

[Sub MandrelParticipant @submandrel]

I'm going to 'bump' this in case my way of posing the questions made it look like I knew the answers – I don't!

The main question is – will 2" diameter wheels be OK for a 5" gauge driving truck?

Neil

[BazyleParticipant @bazyle]

They will work technically. I prefer to see bogies on a driving truck just because it looks better proportioned in which case they will certainly work. 4 wheeled trucks especially small wheeled ones look like they are straining when they go over joints.

Just measured my footrests. Inside edge between the verticals is 16.5 in and 13.5 in from rail top to underside. However I have no idea how much clearance that gives just that you will be able to tun on the St Albans track and at least half of hte Basingstoke track which is where out old track ended up. Also it is 18 in from bum to footrest which is comfortable.

Width of seat is 9 in which is also about scale width of a waggon in 5 in and length of sleeper. If you think about it most tracks get built with about 5 in scale sleepers so that plus a couple of inches tends to be the width of the structure. Make the footrests detachable and invent a good quick release so there is no faffing around at the track. No diddly little screws. Make a second set for ground level track that end up just above track level. Length of bogie truck would end up 25in min. Mine is 32in but not long enough for 2 except maybe children.

Remember as you lean forward to tend the loco your c of g needs to stay behind the front axle.

Brakes are most ly not used but when you need them – well it's too late to go back to the workshop and fit them. Some tracks might not allow you to run without them. However don't worry, they are easy to make using bike brake blocks and a bowden cable allows the lever to be anywhere convenient.

[Sub MandrelParticipant @submandrel]

Thanks Bazyle,

I'm not worried about looks just yet, I want to avoid having to borrow a huge truck for my tiny shunter!

I have some 2 1/4" bar, enough for four wheels and bit more (the flywheel on a small IC engine I hope) so you've given me the confidence to go for that. I didn't think of swappable footrests – I'll do that although I only have a 3 1/2" gauge loco at the moment.

I've made a seat with leather over dense foam on a blockboard base, welded up a chassis from 2mm tube yesterday. Making it about 28" long so probably much too short for 2.

I found a large square of rubber in the road the other day, 10mm thick and quite resilient, it appears to be a lorry mudguard! It hacksaws surprisingly easily, so I'll use it to make resilient suspension mountings, with the length this should help make up for small wheels.

Neil

[Kerrin GalvinParticipant @kerringalvin72662]

Hi Neil,

My I suggest that you hunt out the M.E. articles by Dave Hudson. He did a lot of research into springing & wheel profile & came up with a very good design, I have being building 2 for longer than I care to admit! I have had a trial run when I got a rolling frame & it is amazing how smooth the ride, & how the boogies track…..all to do with the wheel profile. He has designed ai 5" 4 wheel driving truck, & an 8 wheel passenger version. Both versions have fully balanced disc brakes per axel, either hand or vacuum operated, the full size passenger version has provision for the brake to be operated by the guard as well. As usual for model engineers I have modified the design for the 8 wheel version for both 71/4 & 5" ground & elevated!

Cheers Kerrin

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

Just a few things thought about from when I ran my Tich many years ago :

(1) Because a Tich size engine has not much weight it can be derailed by the pull and swing of the driving car if draw bar and buffers set up is not right .

The line of pull should be at the same height on engine and driving car and as far as possible in a straight line when engine and car are on straight track . For a 31/2 – 5 combination this means having an offset draw hook on the car . Draw bar itself has to have free movement up and down and side to side and not be too short . Ideally the whole draw bar system would have some give in it – some of your rubber blocks behind the car draw hook would be ok .

Buffers have to match on engine and car as well and this means offset buffers on car for 31/2 – 5 combination . That's ok for one 31/2 engine but a different set of buffers would be needed for a 5 engine . Some people resort to big plain blocks covering all possibilities . Again some give would be ideal – ruber blocks agin with stel facing a nd curved at least in horiz plane .

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

The actual drawbar system can be a hook on engine , hook on car and loose chain betwen but many people prefer to use a pin connection each end and a one piece drawbar . Ideally this is slotted at the car end to allow engine buffers to close up to car buffers when stopping rather than put drawbar in compression .

(2) Wheels ideally all have ball races . If the proposed running track is likely to have tight curves then there is considerable advantage in having each wheel free to turn independently . Where wheels are very small , as you propose , this is easily done by fitting one deep groove bearing in each wheel and using dead or stub axles .

(3) With very little engines you don't want to sit too high up – its a long way down to the regulator .

Michael Williams .

[BazyleParticipant @bazyle]

Interesting source of rubber. Mouse mats are another.

FYI roller skate bearings are the cheapest. I heard that from the bloke at the Bristol Exhibition with a CNC wood router who used about 4 dozen of them.

With a solid bar drawbar you won't need buffers. If you use a plain hook consider a safety chain too as backup.

Photo of the Dave Hudson truck anyone? – else I will have to go and dig out the magazine. (lazy sod mode on)

[Bruce VoelkerdingParticipant @brucevoelkerding91659]

A late member at our local track had a beautiful original Royal Scot in 3-1/2" gauge, an absolute delight to drive. His driving truck had a very simple brake. There was a lever on the side atached to a cross-shaft mounted on the frame. I do not remember the detail construction, but it just swung a "brake" pad (approximately 5" square) down onto the rails. I seem to remember it was suspended at its trailing end by a swing link of same radius as the leading operating arm, so the pad remained horizontal as it swung down paralllel to the track (but forwards so it would not grab and de-rail the driving car). A spring was used to hold the brake off.

Since our track was close to dead level, one could apply a light pull to the brake and load up the locomotive. Due to its size and chamfered leading edge, it never caused a derailment. Since it wasn't a bunch of tiny parts rubbing on wheel profiles, one never felt guilty using it lap after lap.

Bruce,

North East Ohio Live Steamers, USA

[Sub MandrelParticipant @submandrel]

Lot's of interesting ideas.

For my trial I was using a big truck with buffers only for 5" gauge – i was warned to keep a hand on the engine when slowing down. I already guessed a big plate on a bit of rubber would be a good idea.

Their coupling bar wasn't going to work with my scale coupling, I took a ring off my keyring and used that to join them. I'll make a bar with one of those scissor QR clips as used for some dog leads.

I've already welded up a chassis to suit live axles, so I hope it will be OK with plenty of 'flex' in the suspension – for sideways twist as well as up down.

I worry some clubs may not like the 'plate brake' – it will be easy for me to fit a disk or band brake mid axle.

Thanks for all the idea

Neil

[John Stevenson 1Participant @johnstevenson1]

When I used to drive trucks for a living, brakes were optional extra's

John S.

[Sub MandrelParticipant @submandrel]

My dad says the same. He came out of National Service where he drove everything from tanks to being a despatch rider (Royal Engineers). He drove quarry lorries for two days and walked out as it was far more dangerous than being in the army – and he was a trails rider too, so no stranger to risk.

Neil

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