Class 37 Locomotive Suspension Springs

I am trying to establish the specification for the (16No. in total) suspension springs as fitted to the Dan Jeavons design, circa 1995, for the cast aluminium power bogies on the Class 37/50/55 battery/electric locos. It is the physical size/number of turns/material and spring rating I require, so that I can form a base line for different loading and track conditions.

Roger. I have become the proud owner of a box of 30yo parts that are referred to as a DJ, Type 37, cast aluminium kit - complete with very faded drawings. In my box of many parts, I may have some spring info, but are you still looking for this?

If at all possible, I would be very grateful if you had any soft copies of pics or drawings that would save me some time recovering ancient drawings!! Thank you. Stay safe

Oliver, I do have my 37 up and running. I belong to three clubs two of which are raised level tracks the third is a ground level. It was on the ground level track that the locomotive constantly derailed but it ran well on the raised level. The springs initially fitted were quite stiff and we replaced them with softer springs but it still derailed on the ground level. We now think it might have been the machining of the wheels and flanges. The springs we fitted were arrived at by guesswork and trial and error.

With regard to the drawings the only ones I have left ate paper copies of drawings nos. GR/1 to 4 inclusive. I believe Mr Jeavons has now retired and the business is now under the ownership of sad castings (Steam and Diesel Castings).

I wish you all the best with your project and a very Merry Christmas. Roger

Roger. Interesting spring experiences. Tis indeed encouraging to see that I am not the only "37" man in the UK. I do have very faint, copies of the main drawings that I have scanned into A4 size and processed the scans to have something that I can machine items, to -- in general. Where I am struggling is having a visualisation of the sub-assembly and then assemblies of the various bogie components. If you are local to Bristol, I could perhaps pop along to see your beast in the flash ...after lockdown concludes!!

I started my 5" loco career with a Maxitrak Type 66, which was an excellent kit and has proved to be a reliable runner on public running days. As I had no problems with this sticking to various tracks, being forewarned of spring issues with the 37 is a good insight.

Thank you

Roger

Just a thought about springs .... I am aware of a similar de-railing issues with a carriage when run on either a raised or ground level track. In this instance, the carriage structure was very stiff and the centre fixings on the bogies were very tight fits. This results in a wheel lifting where the rail levels are different , which caused the derailment. If you have not done so, checking the clearance on the bogie centre fixings may save you the trouble of tweaking springs. HTH

Ex member of our club had a 37, the springs were preloaded to such an extent that you couldn't move them. Even with all batteries installed and my considerable weight applied they didn't budge. As I say he's 'ex', so I can't ask him whether it us a Jeavons design, but he had endless problems with adhesion, which I put down to no effective suspension

Oliver, Unfortunately I live at the opposite side of the country, as far from Bristol as it is possible to get, on the SE coast. I live closer to France than Bristol. Sadly I can't just pop round for coffee and a chat. I will investigate the spring aspect a little further having received some good guidance in the last 24 hours.

With regard to other detail please PM me.

Hello Duncan, On one raised track at one point if I get a signal check, I get a lot of wheel spin when pulling away and I put this down rightly or wrongly to oil on the track. It came as a bit of a surprise to me considering the weight of the locomotive with 2 twelve volt batteries and just two of us riding behind the loco. When the weather improves and Covid permits I can get the locomotive out and experiment some more having received your advice. There are two sets of springs and the only set I have changed so far the springs to the suspension bar. The springs to the suspension member are as supplied. The drawings incidentally cover the bogie detail for classes 37, 50 and 55.

Adhesion is one of those 'brain hurting' problems. However, with non coupled axles, if one wheel either loses contact with the rail due to a dipped joint, or loses friction due to a spot of oil, all the torque which was shared between 2 wheels on one axle now has to be taken by one wheel, the rail/wheel interface force doubles, and this is likely to cause that wheel to slip, so the axle spins. The coeff of friction drops rapidly once a wheel is spinning, so it doesn't necessarily stop spinning once the bad bit is passed. This doesn't happen to the same extent with coupled axles, if one wheel out of 6 loses all traction, the others have to take ~20% more, so less likely to slip. Locos on heavily loaded freight trains have slip detection which controls individual axles so that the slipping speed (wheel relative to track) is very low and the coeff of friction doesn't plummet. I've got a curve of friction vs slipping speed somewhere if anyone is interested, but it won't cover cast iron wheels on aluminium track.

Out of interest, I have been experimenting with Rubber blocks for the 37, central suspension as the specified springs do seem to be rather soft. I have experience of building David Hudson centre-less bogies, which use rubber components, and the suspensions is remarkable.

As the Hudson rubbers are too big for the Class 37 structure, I have been conducting some preliminary tests using rubber spacers on with an unfinished loco. It has been possible to establish rubber suspension systems that range from "harder than the Hudson rubbers" to softer than them.

The source of the rubber components is www.hawkeng.co.uk , I bought all three Shore Hardness grades available so that I could test everything out. I used the spacer kits with a 4mm hole, The kit allows for a length of suspension upto and beyond the specified spring length of 1". The actual length for any specific loco will depend upon the length of central bolt and the harshness/softness preferred for that loco.

These rubber components are much cheaper than conventional springs, and I suspect, just as serviceable, when battle tested.

I just took a simple approach for my class 22 suspension springs which copies how I sprung my 0-4-0 shunter. I use die springs and on the shunter I went with springs that are approx 30% pre loaded when the battery is fitted and ready to run. I have 12mm of travel in the suspension so the springs are compressed by 4mm leaving 8mm for operation.

The shunter has excellent traction, no spinning so I have based the 22 suspension on the same hoping it will run just as well. Obviously the 22 is bigger and heavier than the shunter so the spring strength is rated accordingly but still with the 30% pre load.

Edited By Ron Laden on 14/03/2021 06:51:24