Heljan O Gauge diesel bogie wheel replacement ?

Discussion in 'Workbenches, including workshop techniques.' started by thruxton, 10 July 2018.

  1. thruxton

    thruxton Western Thunderer

    Just wondering if anyone has experience of changing these wheels for another make, and any tips on methodology?

    The question arises from me currently using Heljan Class 47 bogies on my 18100 scratch build. The wheels should be spoked and I'm debating the odds of rewheeling as an option to overlays.
     
  2. eastsidepilot

    eastsidepilot Western Thunderer

    What ever wheels you use they will obviously have to be insulated from the axles, so if you can source a cast wheel that can take a bore large enough to take the Heljan wheel axle bushes, this would seem to be the simplest method.
    The alternative will be Slater's plastic jobs I suppose but then you'll be messing around with re-bushing to take the small dia. axles.

    Current collection on the cast wheels could be as the original Heljans, if there is enough meat on the castings you can turn an appropriate guide on the back of the wheel, the Slater's might be a problem, just more work.

    Col.
     
    mickoo and daifly like this.
  3. thruxton

    thruxton Western Thunderer

    Hi Col

    Actually, I've been looking into spare Heljan bushes before I risk damaging those on my existing bogie. Sizes appear to be a 3mm axle bore with something like a 3/16 interferrrence fit to wheel. There is a potential alighnment issue insofar as the Heljan wheel plus pick up collet provides around 10mm bearing area on the bush- replacement wheels would have only half or less. Additional bushing might resolve this, as would a suitaly sized sheeve/pulley wheel at the rear side of the wheel (allowing retention of original pick-up).

    Any off the shelf wheels are likely to be steam/con rod oriented but the 18100 frames are accomodating in their depth and can hide multiple sins.
     
  4. simond

    simond Western Thunderer

  5. Steph Dale

    Steph Dale Western Thunderer

    This seems like a bit of an ask for me - the class 47 is about 2'8" longer in bogie wheelbase and Co-Co; 18000 is A1A-A1A so needs smaller centre wheels. You'll surely have to compromise the bodyshell to give clearance for the longer bogie? And compromise the bogie itself, both for length and the wheel diameters?

    I also suspect that the wheels would have an odd number of spokes (relatively unusual in the UK); thankfully they don't have typical German/Swiss webbed spokes!

    If you want to use an r-t-r bogie, would a Western not work better? It's only a couple of scale inches too long.

    Steph
     
  6. thruxton

    thruxton Western Thunderer

    Seph

    I think you may be confusing 18100 with 18000- I have made the rolling chassis for both. In 7mm, the Heljan 47 bogie is around 1.5mm short on wheelbase for 18100, but this is a bit of a benefit given the tight clearances. Few, if any dimensional compromises have been needed and both designs would accomodate Scale 7 wheelsets. 18000 is indeed A1A and mine sits on ABC bogies, spoked wheels of course.


    Simon

    Walsall would be my first choice , 'scale' would be 3'8" 10 spoke (I think) for which they have an adaptable 3'9" tender variety. I have found Walsall to be very helpful with bespoke requests.
     
  7. Steph Dale

    Steph Dale Western Thunderer

    Aah yes, it appears I might!

    Steph
     
  8. mickoo

    mickoo Western Thunderer

    Rather than re-bush the bogie and I presume gears, I'd be more inclined to sleeve the Slaters axle out to the correct dia, so that it fits the existing bearings and gears, NS tube or a steel sleeve turned up would suffice. Any concerns over slippage between the two would be resolved with a suitable adhesive and a pin for extra security.

    7843SWMF 3'-7" ten spoke
    7845SWMF 3'-9" ten spoke

    Both would suffice, you'd be hard pressed to spot the 1" difference behind the bogie side frames but if it was irksome then opt for 3'-7" and have part worn wheels.

    As a test just buy one set of wheels and give it a try.

    MD
     
  9. simond

    simond Western Thunderer

    Mick,

    I’m not familiar with the Heljan bogie, but if you have axles with gears that fit the bill, and you need spoked wheels, and you can get castings, why wouldn’t you simply do the wheels?

    Bushing axles to fit gears & bearings and modifying pickups sounds like harder work than turning the wheels? (Presuming you have access to a suitable lathe, of course)

    Best
    Simon
     
  10. thruxton

    thruxton Western Thunderer

    For those unfamiliar with the Heljan O Gauge et-up, at least early stuff such as mine;

    - motor and bogie are a unit (ie no drive tower such as is becoming common in OO),

    - gear train is nylon with a tight fit final on the axle- it is understood to be unwise to try and remove this final cog wheel for fear of splitting,

    - wheels are solid metal with a plastic bushed hub press fitted to the axles,

    - pick up is via spring wire wipers which sit in a pulley/sheeve shaped boss on the wheel backs (quite prone to slipping out of the grooves when handling)

    - on CoCo's the central axle is floating

    I am not sure about 7mm scale, but I understand early Heljan British Outline wheels could easily attract enough muck to cause running problems (brass?). OO wheels are now of a different material.
     
  11. eastsidepilot

    eastsidepilot Western Thunderer

    Thruxton,
    I'd use the Walsall wheels, there may be enough meat to turn a sheave on the back and bore for a insulation bush to mount on the Heljan axles.

    The early Heljan wheels are rubbish, the tyres are turned square ( no coning ) and the flange is just like a top hat bush !
    If anyone needs so called F/S Heljan wheels improved I have a F/S profile tool.

    Col.
     
  12. thruxton

    thruxton Western Thunderer

    Col

    That is my current thinking- the rear boss is a bit of a red herring for the 18100 where chassis and bogie skirts would readily mask modified wipers or plungers.

    From responses so far, it seems the complete replacement of Heljan wheels is a rare thing (?) or maybe their models are not (yet) much used for kit bashing (?).
     
  13. eastsidepilot

    eastsidepilot Western Thunderer

    Must admit I've not heard of anyone using the running gear on kits/scratch builds etc. I've lost count of how many I've converted for my S7 colleagues, the wheels are easy to re-profile and the axles are just long enough to re-use, although I don't like the material they are made from.
    If I had an auto lathe I would knock out some decent steel jobs.
    If I was converting one for myself I'd turn up replicas from cast iron.

    Col.
     
  14. simond

    simond Western Thunderer

    Thruxton

    You should be aware of a Jim Snowdon’s work on the GoG forum to prepare replacement brass gears for some Heljan bogies.

    I’ve vaguely followed the story from a position of no skin in the game as I don’t do diesels (apart from the Ixion fowler & a freelance Mavis built around 18 years back for my son who’s now 20) so I don’t have the details, but can go find the links if you need them.

    Iirc, he did final drive gears for several, but not all bogies, as the spares situation is dire, and the replacements were liable to split too.

    HTH - let me know if you need more info

    Best
    Simon
     
    Last edited: 13 July 2018 at 23:35
  15. thruxton

    thruxton Western Thunderer

    Hi Simon

    I was reading about these only last week. Should I go the rewheeling route, brass gears might be a sensible investment. As things stand I have four pairs of nylon spares courtesy of Howes. It is worth noting they often have stock when their website shows zero.

    Penny pinchers among us will be pleased to know the cosmetic add on spokes are beginning to look promising!
     
  16. simond

    simond Western Thunderer

    Yes, I can see how that might be the case

    If it were me, I think I’d want brass gears and cast wheels...

    I’m sure you can sell off the nylon gears!

    Best
    Simon