Atlas Plymouth to Hibberd Planet conversion

[Dava]

This is my first topic so please bear with my slow grasp of the technology....

 

I suspect I'm not alone in having acquired an Atlas 6-wheel Plymouth switcher loco and wondering quite what to do with it. They can usually be acquired at GOG meetings for £20 or so. As a US prototype in 1:48 scale, it is too wide and low to pass for a British loco and my well-used example was too rough and 'clonked' when it ran to be sold on, so I had to find a use for it.

 

Being in need of a small shunter to test track and generally be useful on my light railway, I worked out that it could be converted into a small 4-wheel loco with a short wheelbase of 5 scale feet in 7mm scale. The result is not a scale model of a Hibberd, but a chunky and useful loco which fits into a British layout more readily than the Plymouth. I could not find a drawing for a Hibberd but there are lots of photos on the internet - such as http://flickrhivemin...erd/Interesting

 

Major surgery is required, but this requires determination rather than any advanced engineering skills. This is a robust loco and you are unlikely to put it beyond use by taking reasonable care. Completely dismantle the entire mechanism, even the motor and all gears are removed for re-use. The front 30mm of the cast chassis is cut off, removing the first axle slot. This takes 20 minutes determined effort with a junior hacksaw and marks the point of no return! The shortened chassis is then cleaned up to remove any burrs and metal dust, and put on one side.

 

Next, the plastic footplate is also shortened by a similar amount, leaving 1mm or so longer in the remaining rear end than the length of the chassis block. The front end pilot is then shortened to fit this, with the chassis block fitting snugly in the centre. The two parts of the footplate need to be narrowed by 2mm each side, resulting in an acceptable scale width of 8'6". Thiis was the hardest part and I found a fretsaw with a blade for wood/plastic was able to do this. The two parts of the footplate were then aligned carefully on a glass surface, and welded together with Butanone, which works effectively on this type of plastic, The plastic side frames were also shortened by a similar amount, and the detail of the old front axlebox and spring filed or cut off, to be replaced later with front steps. My model already had power collection on the old centre axle (now the front) but otherwise this would need doing. Finally the keeper plate is shortened at the front to fit.

 

After thorough cleaning, the chassis is reassembled, using the flanged wheels in both remaining axleboxes and not using either the flangeless wheelset or surplus large gearwheel. It should run quite acceptably, but may need minor adjustments.

 

The next step is to select the design for the body. For the Hibberd, I used the front 55mm of the Plymouth bonnet, with the name, light and exhaust stack detail filed off, although I left the louvres on the engine side doors. I used 40thou plasticard to build a cab, based on the Hibberd design with its characteristic sloping roof, and added waist-level beading from microstrip. As there is no cab floor, I included a false sloping roof to reinforce it, then added a 10 thou overlay for the final roof surface. The cab sides were reinforced with sections of the old Plymouth cabsides below the windows, with the detail filed off. Full-length buffer beams were also made from 40 thou with a 10 thou overlay onto which rivet detail was embossed first with a scriber. I added the distinctive channel side frames from 40 thou below the footplate and used offcuts to build the cab steps.

 

Brass buffers, 3 link couplings and a range of little details such as handrails, a horn and light on the cab front was added, before spray painting in Doncaster green and finishing. The end result is a powerful small loco which runs quite slowly for shunting and is very robust.

 

OK, tell me you hate it!

[shortliner]

From an out-of-scale toy, to a useble shunting loco - excellent, Sir! Very well done!

[Mike Bellamy]

Perfect - I have one of those locos and I now know what to do with it - eventually !

 

Mike

[HeavyDuty]

OK, tell me you hate it!

 

Nope, not going to happen.

 

I think I may have one of these tucked away from back in the 70's. A very nice conversion!

[hartleymartin]

This is excellent! A prototype to aim for!

[hartleymartin]

If these are of any help, I went and took some estimate measurements of photos of prototype Planet locomotives using known dimensions such as width between buffers, height of buffers, gauge, etc in photos:

 

6'6" wheelbase

17'8" length over headstocks

6'0" Cab length

10" back of cab to rear headstock

8'4" length over hood

4'4" height of hood

11'3" height over cab (approximated)

8'10" height of cab sidesheet

5'8" rear axle to rear headstock

5'7" front axle to front headstock (make even for front and rear)

9'0" headstocks width

6" clearance headstocks above railhead

7'9" cab width

8'10" cab height above footplate

4'6" height of strip on cabside/cab-back from footplate

Rear windows: 24" wide, 20" high

[Dava]

Hartley,

 

These are really useful dimensions... if I'd had them a few months ago I probably wouldn't have claimed that the Atlas conversion I built represented a 'Planet', as very few of these dimensions match the loco I built - length is closest - because of the limitations of building it around a shortened Atlas chassis.

 

I had an operational need for a small shunting loco to test sections of track and bat a few wagons around on the small layout I'm building. The radical surgery on the Atlas provided this and put what had been a redundant acquisition to work. Atlas locos don't like PECO points, because of the wheel flange profile, by the way!

 

What we really need are dimensions like this matched to a drawing of one of the Planet variants - there were several. Then either scratchbuilding or a kit to produce an authentic Planet will be much easier.

 

Dava

[hartleymartin]

I think the feature that makes it distinctly not a Hibberd Planet locomotive is the louvred door panels. I have never seen a planet with them. However, you have made a very good looking little locomotive out of what was a poorly-scaled 1970's toy. Who is to say that Hibberd did not manufacture a few special orders in its life time to suit particular local conditions?

 

As you, yourself have said, that you have managed to put an otherwise redundant acquisition to work. It is infinitely more believable than the original Atlas Plymouth Switcher. I hope to make a similar conversion, using one of these models which I acquired quite cheaply. I am surprised that you find the Atlas wheels to have troubles with Peco points. check your back-to-back dimensions on the wheelsets using some callipers. I have had few such difficulties thus far.

 

I also agree that some good scale drawings of various models of Hibberd Planet would be most helpful, since they are a fairly simple outline, which would not be too difficult to scratch-build.

[marc smith]

I too have one of these,

though I paid a bit more for it....

It runs pretty well as-is...

and I've not had trouble with Peco points

- maybe it is your back-to-backs, as above poster has said

 

You've done a nice job on that conversion

and although it may not represent a prototype loco 100%

it looks convincing enough...

(there are plenty of differing designs of industrial loco about)

 

I'll have to set to work on mine now!

 

Thanks for posting

Edited October 15, 2012 by marc smith

[hartleymartin]

I also think that you particularly captured the Hibberd style of cab quite well.

[d600]

Hi im about to do your conversion on the atlas Plymouth where do you measure the 30mm from to cut the footplate to length from the front or the rear of the plastic footplate and could you tell me how long the length is of your completed loco not including buffers. 

 

cheers

[Dava]

Let me get back to you on that, the loco is boxed up in the workshop at present!

[Andrew Young]

Only just found this thread. Just wondering whether one of these chassis' would make a suitable basis for the Kerr Stuart 6wDM No 4421 infernal combustion loco that ran at Ravenglass and is now on display at Foxfield: http://www.flickr.com/photos/dc-7c/6274583191/

 

I have a drawing somewhere, if I can find it?!

 

Cheers,

Andrew

[Dava]

Answer to d600:

 

The length of the completed loco is 128mm over buffer beams

 

The 30mm plastic footplate to be cut off was measured from the front buffer beam

 

Hope this helps! Good luck.

 

Dava

[F-UnitMad]

It was my impression that the Atlas O scale Plymouth was reasonably accurate?? Any HO & N versions from various makers were always too big.

I like the chassis conversion though, as there do seem to have been many more 4-wheel Plymouths than 6-wheelers.

[Dava]

If anyone is interested, the 'Planet' loco conversion I built is available for sale, at a modest cost, as Coney Hill is now well supplied with small diesels. I've been working on the 02 and Fowler today. PM me if interested.

 

Dava

[Dava]

Final appearance and farewell to the 'Plymouth Planet', here posed with two other green diesels which have replaced it, before being packed for export to a 'mystery buyer' in Australia - bon voyage!

 

 

 

Dava

 

 

 

[hartleymartin]

I confess that I am the buyer of said Planot loco. I'm waiting for my January holiday period to get the layout built so I can start running it.

[Dava]

Martin,

 

Hope the layout idea works out. I am hoping for a quiet patch to finish unpacking boxes & build a little layout next year. But work, books & a campaign to save our local rail line here in Cape Breton get in the way!

 

Dava

[hartleymartin]

Just an update on the old "Planot" Loco. She's been working for a few years now in Australia, where the new owners have done a little work to help it suit local operating conditions. There are now hand-rails along the hood, new door handles on the louvred side panels, and larger buffers for shunting duties.

I also took the opportunity to correct an issue with the weight balance. She was a little "tail-heavy" and had a slight tendency to pull a wheelie if the driver was a little heavy-handed with the throttle.

 

[hartleymartin]

She has also become No.5 with a rather nice set of brass number plates, which have presumably come off another old loco at some point.

[Dava]

Good to hear this refugee is still in good hands and proving useful. I liked the Planet which Sir Douglas scratchbuild as it was more accurate. I still have too many green diesels [they're all green!] and more on the way. I am building an 014 layout which is all-IC [one petrol Planet, the rest diesel until I do a battery electric and Sentinel steam loco].

 

Dava

[Turin 60]

 

Just an update on the old "Planot" Loco. She's been working for a few years now in Australia, where the new owners have done a little work to help it suit local operating conditions. There are now hand-rails along the hood, new door handles on the louvred side panels, and larger buffers for shunting duties.

 

I also took the opportunity to correct an issue with the weight balance. She was a little "tail-heavy" and had a slight tendency to pull a wheelie if the driver was a little heavy-handed with the throttle.

 

May I ask what the mods are you carried out to improve the balance?.

 

John.

[hartleymartin]

I just put some lead under the front of the bonnet.

[Turin 60]

I just put some lead under the front of the bonnet.

Ahh, the simple answers are always the best, I was planning on drilling out the casting around the motor to improve the balance.

 

Thanks John.