EE Type 4, D211 with PenBits sprung chassis

Dave Holt
Posts: 422
Joined: Thu May 28, 2009 9:44 pm

EE Type 4, D211 with PenBits sprung chassis

Postby Dave Holt » Thu Jan 31, 2019 10:01 pm

As a change from my more usual steam loco models, I am working on a Bachmann Class 40 with sprung chassis which has reached the stage of being a functional loco but still devoid of much of the detailing work required to make a convincing model.
Here are some photos showing various stages of the work done to date.
This is the current state of play.

assembled model

I'm not entirely happy that I've got the cosmetic frames attached quite right. They look to droop down towards the outer ends slightly so might have to do some rectification before going any further.
To reach this stage, the PenBits chassis kit had to be assembled. It consists of an inner bogie frame, which carries the sprung axle boxes and into which the modified Bachmann drive train is fitted, floating on the driven axles. The inner frame is carried in a mounting tower, on secondary springing, which carries the cosmetic side frames and mounts into the Bachmann chassis block in such a way as to allow the bogie to pivot sideways but not pitch up and down longitudinally. However the inner chassis can rock for/aft on the secondary springs, to accommodate humps and hollows in the track enabling the cosmetic frames to be mounted close under the body, as per the prototype.
Here's the inner frame, axle boxes and radial front truck.

inner with pony

And then with the primary springs fitted.

inner side view with springs and axle boxes

The inner frames are mounted in the tower unit.

chassis side view, with springs and axle boxes

Some fairly drastic butchery is required to the Bachmann drive train to allow articulation over the three axles in the bogie. Twist is accommodated, slightly crudely, by enlarging the axle bushes in the Bachmann drive train. The drive gear teeth are quite course and can remain in mesh despite this.
The Bachmann final drive gears have to be drilled out and fitted to the new P4 axles. A friend from the P&O Group kindly did this for me using one of his watchmakers lathes. I used Alan Gibson diesel driving wheels on 2 mm axles. The extended truck axle also seen was recovered from and earlier Lima conversion and modified to fit into the BenBits radial truck frame.

cut drive train


The drive train is re-connected by a link, which carries some of the drive gears. Here it is in front of the PenBits frames and tower.

chassis and drive train, separate, side view

chassis and drive train, separate

And then placed inside the Penbits inner frame.

inner frames with extended drive

Here's the whole lot, loosely assembled without the axle boxes or springs.

loose assembly trial

The Bachmann cosmetic bogie frames are modified to fit around the mounting tower and are quite flimsy until fixed. Apart from the use of separate foot steps, one of which I've managed to snap off, I honestly think the mouldings on the old Lima model are better than the latest Bachmann effort. So much for progress. I also opened out the holes where the front truck extended axles stick through the side frames.

cosmetic frames

The inner chassis were then assembled with the wheels, springs and some bus-bar pick-up mounts. The chassis kit is designed for wheels shorted out on opposite sides of the two bogies, but I chose to fit phosphor bronze wire wipers bearing on the back of the rims of the outer axles on both bogies (not shown in the photos). These did cause some shorting problems during initial testing due to the tight clearances withing the bogie/tower assemblies, but I got it sorted, eventually, by moving two pick-ups on each bogie. The bus-bars have to be articulated to allow for movement of the drive train sections, hence to insulated wires.

inner chassis, side view

inner chassis

Before I powered up the assembled chassis for the first time, it was fitted into the chassis block and body, with the worm and drive shafts omitted and pushed through the station throat point work on my Delph/Holt layout, to check that it could cope with the various reverse curves, etc. I can't remember now whether i tried it on the very tight curve into the mill siding or not. In any case, it never be required to do this during layout operation, so doesn't really matter. I'm confident it can negotiate normal curves and cross-overs it might encounter in use.

test on delph

So, some possible rectification of the cosmetic bogie frames and then pipe work and other details.


User avatar
Jonathan Hughes
Posts: 93
Joined: Thu Sep 29, 2011 9:31 pm

Re: EE Type 4, D211 with PenBits sprung chassis

Postby Jonathan Hughes » Fri Feb 01, 2019 3:47 pm

Excellent work Dave. Ian certainly produces a fine springing kit and the 40 is certainly going to be among the most complex, but that all looks rather tidy and inspiring.
Thanks for sharing this

User avatar
John Donnelly
Web Team
Posts: 864
Joined: Fri Mar 16, 2012 7:03 pm

Re: EE Type 4, D211 with PenBits sprung chassis

Postby John Donnelly » Fri Feb 01, 2019 8:00 pm

Nice work so far Dave, I'm about 80% of the through the Penbits 45 bogies which are very similar.

Jeremy Good
Posts: 159
Joined: Fri Feb 19, 2010 10:36 pm

Re: EE Type 4, D211 with PenBits sprung chassis

Postby Jeremy Good » Fri Feb 01, 2019 8:34 pm


It's looking good...

I found the Peak chassis, which is to all intents and purposes the same design, one of the easier ones of Ian's chassis to build. It doesn't have the complicated brake gear of a 26 or 37 and despite the need to build an extra bolster to move the bogie pivot point is pretty straightforward.

With mine I decided to take the live axle route on one side of each bogie by soldering the shorting discs to the backs of the wheels. I did have to take a deep breath before I did this on a set of Ultrascales but all worked out fine and it takes away the need to set up the pick-ups which I always find a bit hit and miss.

Like you I have found the design (in my car a Peak) very sure-footed even on the fairly tight turnouts of my china clay layout and the pony truck behaves well all the time. Another well designed chassis kit from Ian.


Return to “Diesel and Electric Locomotives”

Who is online

Users browsing this forum: No registered users and 1 guest