Bachmann 4MT & 5MT EM/P4 conversion: re. brake gear

[philsandy]

Can anyone advise how to modify the brake gear on these 2 locos after gauge widening.

I have converted Bachmann locos before and either chamfered the backs of the brake blocks to clear the wheels. Or cut the blocks off the keeper plate, and glued them back on, plus approx. 1mm of packing.

 

It does not seem possible to do this with these 2 models. The brake blocks are too thin to start with to chamfer.

And if you cut the blocks off and re attach, plus packing, the brake rigging underneath will then not clip in to the small holes on the blocks, as they are now wider apart.

Any advice most welcome.

 

 

 

 

[NFWEM57]

On 04/07/2016 at 20:58, philsandy said:

Can anyone advise how to modify the brake gear on these 2 locos after gauge widening.

I have converted Bachmann locos before and either chamfered the backs of the brake blocks to clear the wheels. Or cut the blocks off the keeper plate, and glued them back on, plus approx. 1mm of packing.

 

It does not seem possible to do this with these 2 models. The brake blocks are too thin to start with to chamfer.

And if you cut the blocks off and re attach, plus packing, the brake rigging underneath will then not clip in to the small holes on the blocks, as they are now wider apart.

Any advice most welcome.

 

 

 

 

Hi,

 

Late I know, but taking up the hobby again after 50 years.

 

Just converting a few Mainline split chassis 4MTs and Bachmann 4MTs and a 5MT to EM.  I decided to use Alan Gibson wheels at first which introduces a whole new range of problems with pick up for split chassis.   For the brake gear, initially I thought there was only one choice, remove completely and fit new. I obtained replacement sets from Comet but they are all metal.   In hindsight the better thing to do would be to remove the blocks, add the padding and manufacture new rigging in plastic or metal.  On the wheel choice for the non split chassis locos, I decided to retain them and manufactured new shoulder axles since at least one loco was factory weathered and the balance weights are already in place on existing wheels; not so AG.  Back to backs are on the lower limit at 16.3mm but the loco did run.  Where I did use AG wheels I retained the original motion sets, where possible, and simply tapped the AG wheels to 1.4mm.  I will be uploading a couple of threads on 4MT/5MT conversions later in the year.  Where the motion sets were damaged or missing, no choice but to make new ones, again Comet.  Pick ups for split chassis is best resolved by adding separate pick up strips to the side of the chassis to touch the AG wheel rims, or those little DCC Concepts pickups underneath.  Adding shorting straps as suggested in some guidance damaged the AG wheels and causes back to back problems, the shoring strips have a finite thickness and the AG wheels have a raised portion at the back in the centre of the wheel. So adding all these 'shims' together means B2B impossible to achieve without fouling on the chassis.

 

For DCC, I removed a healthy portion of the front of the chassis of the 4MTs to make room for a 6 pin decoder.  Only one function need for light if fitted. 

 

Patrick

[philsandy]

Patrick,

I have no experience/knowledge re. split chassis locos.

On most of my EM conversions I have used the original Bachmann/Hornby wheels, and reduced the flange thickness by 0.2/0.3 mm and used EMGS 3mm/2mm stepped axles.

Problems can arise with the front driving wheels, when there is not enough clearance, and the crank pins foul on the cross slides.

 

As for the brake gear with these 2 models I ended up cutting off the brake blocks and gluing them back on the keeper plate, plus packing, The brake rigging assembly was held in position by the original locating lug at the rear end, and by gluing a piece of plastic to the underside of the front end brake rigging approx. 2mm thick, I put a blob of "black tack" on this and this held it in position to the keeper plate.

So the brake rigging is in the correct position, but not actually located in the brake block holes.

[NFWEM57]

4 hours ago, philsandy said:

Patrick,

I have no experience/knowledge re. split chassis locos.

On most of my EM conversions I have used the original Bachmann/Hornby wheels, and reduced the flange thickness by 0.2/0.3 mm and used EMGS 3mm/2mm stepped axles.

Problems can arise with the front driving wheels, when there is not enough clearance, and the crank pins foul on the cross slides.

 

As for the brake gear with these 2 models I ended up cutting off the brake blocks and gluing them back on the keeper plate, plus packing, The brake rigging assembly was held in position by the original locating lug at the rear end, and by gluing a piece of plastic to the underside of the front end brake rigging approx. 2mm thick, I put a blob of "black tack" on this and this held it in position to the keeper plate.

So the brake rigging is in the correct position, but not actually located in the brake block holes.

Hi,

 

Thank you for the reply.  I have experience of both split chassis and and conventional chassis.  On the 5MT I partially converted, to test a prototype EM gauge turnout from British Finescale in a bit of a hurry (separate thread under templot), I used AG wheels expect for the drivers.  I set the back to back to 16.3mm on the original axles and got away with it, no clearance issues and the loco ran though EMGS B6 and prototype point work smoothly; there are a couple of videos in the thread, March 3rd and March 7th

I will be putting on the AG drivers and using the original motion gear to complete the job with a B2B of 16.6mm.  I have a much later Bachmann factory weathered 4MT and the wheels are a little thinner so i will use them but the 3mm portion of the EMGS shoulder axle will need reducing by about 0.8mm; lathe job.

 

All the best,

 

Patrick