Mainline/Perseverance J72

[Hardwicke]

Some years ago I bought a quick job of a Perseverance chassis and Mainline J72. I've actually got two tops, one BR and one Green. Not so quick as two hornblocks were missing. I found my spare ones last week and using the Avonside Jig, the chassis is set up, ready for wheels, brakes, pick ups, motor and gears.

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[Hardwicke]

I forgot to say the Flexichas beam still needs adding.

[DougN]

Looking good Hardwick, these were always cheap and cheerful. My J72 which is still going and is nudging 30 years old is happy to run around still. Mine had the square bearings rather than the round with a wire to stop rotation!

[Hardwicke]

Mine had the square bearings rather than the round with a wire to stop rotation!

Yes, I'd have preferred square bearings but the lead axle already had the round ones and the bag of bits had two more with the wire ready soldered.

[Hardwicke]

Any suggestions for a motor/ gearbox? I'll be using a High Level one.

[Porcy Mane]

Any suggestions for a motor/ gearbox? I'll be using a High Level one.

For my J72 I used a Slimliner Compact and a small Mashima. The slimliner was needed to clear the High Level hornblocks.

The geabox was slightly modified by reversing the etch through which the axle/final drive pinion passes. This was done to allow the motor to sit lower and further forward , so that a DCC decoder can sit above the motor & to enable the fitting of a backhead.
Nowadays I'd definitly go for one of Chris's coreless motors with them producing about the same amount of power for approx. 60% of the size of an Iron Cored motor. If your a DCC user, I'd consider dispensing with the flywheel.

The U shaped brass plate sandwiched between the motor and gearbox is for mounting the decoder on the upper surface and fitment of a torque reaction bar to the lower.

The chassis used is Mainly Trains although I dispensed with everything other than the sideframes coupling rods and brake assemblies.

Pics below may make things clearer.

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P

[Hardwicke]

Does anyone have a copy of the Perseverance instructions? There are 3 lots of wire in there and I want to know which to use, for what.

[Noel]

The 1/16" rod is to be soldered between the frames as a pivot for the tube, and also presumably provides the compensation beam itself [the instructions are a bit vague] which is attached to the tube. The 0.45mm brass wire is for brake hanger pivots and to join the bottoms of the hangers across the chassis through the pull rods. There is no specific reference to the third wire, which is a larger diameter than the brass, but it appears to be phosphor bronze so is presumably intended for pick-ups; the instructions suggest soldering a short length of brass or gold wire to the ends to provide the actual contact with the wheels.

The instructions I have are poorly reproduced, probably copies of copies, so I've picked out the relevant bits. I am happy to scan the three pages involved if you want them.

[Hardwicke]

I am happy to scan the three pages involved if you want them.

Your post is really helpful and sets me forward again, but if you can scan them I'd be grateful. The MRJ article used a pre production kit, so didn't tell me what I wanted.
Thanks
Michael

[Hardwicke]

How do the J72 brake pull rods fit? My kit doesn't have any and the instructions are generic. I've drilled out some 1mm n/s strip but unsure where to fit it. The NELPS site doesn't really help.

[Porcy Mane]

How do the J72 brake pull rods fit? My kit doesn't have any and the instructions are generic.

First twenty (Short bunkered) had a central pull rod. Remainder had asymmetric pull rods to equalise brake pressure to each wheel. The cross shafts are flat bar approx. 8" wide at their maximum. Some of the first twenty were later converted to asymmetric pull but I haven't as yet been able to confirm which.

One of the best things about the Hi- level J72 chassis kit is that you get three sets of asymmetric brake gear to play with (00, EM & P4).


Pics should make things clearer. The underneath shot is courtesy P Shield.

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[Hardwicke]

How do the J72 brake pull rods fit? My kit doesn't have any and the instructions are generic.

First twenty (Short bunkered) had a central pull rod. Remainder had asymmetric pull rods to equalise brake pressure to each wheel. The cross shafts are flat bar approx. 8" wide at their maximum. Some of the first twenty were later converted to asymmetric pull but I haven't as yet been able to confirm which.

One of the best things about the Hi- level J72 chassis kit is that you get three sets of asymmetric brake gear to play with (00, EM & P4).

Absolutely brilliant. Thank you.
Just what I was hoping someone would post. I thought I could see a central pull rod or something off centre. I can continue building it now.
I broke the drill bit twice making 6 holes in the 1mm strip for two pull rods, but re-sharpened it to complete the job. It went a bit off true.
I could keep the one with the off centre holes as a spare or use it as cosmetic flat bar cross beams, with the actual wire soldered beneath it.

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[Hardwicke]

Oops. The holes are a fraction too small for .45 wire

[davebradwell]

If you're trying to make a central pull-rod it should be round section, just under 0.5 would be scale or 0.7mm at most. In any case, 1mm strip represents 3" so too wide for that type of pull rod - they would be around 2". Unfortunately I believe the first 20 had the earlier frame shape cut higher at the side of the firebox. You'll have to look into whether the bunkers were extended. My drg of the early engines seems to have disappeared so I can't add clarification. Information on details is in the green books, now accessible on the RCTS site.

By asymmetric, do you mean compensated pull-rods? It just means they're in sections and run at a slight angle.

I can't see how you can make any model without a decent drawing. Easiest source is NRM, just look down the OPC list as they work out cheaper as they're from microfilm. I suggest a digital copy and have it printed locally. There'll be several versions of J72 in list with sections being valuable as they're not on GA.

DaveB

[Hardwicke]

If you're trying to make a central pull-rod it should be round section, just under 0.5 would be scale or 0.7mm at most. In any case, 1mm strip represents 3" so too wide for that type of pull rod - they would be around 2". ........ Information on details is in the green books, now accessible on the RCTS site.

By asymmetric, do you mean compensated pull-rods? It just means they're in sections and run at a slight angle.

I can't see how you can make any model without a decent drawing. Easiest source is NRM, just look down the OPC list as they work out cheaper as they're from microfilm. I suggest a digital copy and have it printed locally. There'll be several versions of J72 in list with sections being valuable as they're not on GA.

DaveB

I might solder a piece of wire to the strip and thin it down in the appropriate places. My idea up to now was to drill it at the same dimensions to the wheelbase and brake hanger etched holes so that all the brake shoes should line up in one go with the wheels. I will do the opposite with the more visible cross shafts and solder flat bar to them to disguise the wire. The Perseverance chassis isn't in the same league as High Level. I think I've another Mainline body : the green one anyway....
I'm already looking at going to the NRM for some plans (LMS 10000 for some 12" to the foot modelling and LMS 4P Fowler tank for 4mm).

[davebradwell]

Many kits just have a wire soldered across the tops (or bottoms) of the brake stretchers (these are the flat bits that run across between the brake hangers). Just fit the brakes when the chassis is done, holding them against the wheels by cunning means and solder on the wire down the centre. 0.7 will be stiff enough. You can't see the missing forked joints when it's on the track anyway.

DaveB

[Hardwicke]

A few hours working on the brake linkage. It's not perfect or accurate for a J72 but the kit is nearly 40 !!! years old.
Next one will be better.

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Trial assembly of the brakes.

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Still to add the fake round and flat bits. Tell me if I've got the brake hangers the wrong way round. They're loose and still awaiting the brake blocks.

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[Hardwicke]

Late night modelling session...
Brake shoes added after they and the hangers had been drilled. The Perseverance kit had no provision for location holes.
Sadly they don't really look as good as the High Level ones for a J72

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[Hardwicke]

I only managed one brake last night. 5 more done today. One to finish. Some need folding and cleaning. Spare wire in place to keep the hanger hole free.

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[Hardwicke]

And cleaned up.

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[Hardwicke]

The flexichas beam was also cut, reamed and soldered today. I put a flat on both parts to aid soldering. Just awaits a bit of oil to stop the solder gumming it up and soldering to the frames.

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[Hardwicke]

Test fitting. The ashpan gets in the way. Otherwise it's all good.

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[Hardwicke]

Added some plastic on which to attach the chassis to the body. I might add a soldered nut and scrap brass to the rear for extra strength. The holes for the Mainline chassis in the rear buffer beam have had bits of plastikard inserted and will be glued and filed smooth. During the cleaning of the body interior one of the front sandbox fillers dropped out. It was pretty rubbish anyway so I removed the other one, pending something better.

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[Hardwicke]

Flexi chas compensation beam fitted.

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[Hardwicke]

Anyone know either;
1) where I can get a North Eastern safety valve cover for a J72?
2) which J72's didn't have them in the BR period?