24/04/2021.

Commercial elongating drawbars

I have adapted elongation drawbars on many older models, Jouef, Hornby, Fleischmann, MMM-RG. Here are some examples.

Sometimes Roco 40343 or 40344 are suitable, but this is quite rare as they are very thick. Their elongation is satisfactory. Here is a USI MMM-RG coach equipped with these drawbars.

Roco drawbar under USI MMM-RG

Most of the time, I used nickel silver Makette KKK. Among these, there is the large KKK-1 model, more adapted to bogie vehicles, and the small KKK-2, which I did not use very much because its elongation is rather short.

Here is a KKK-2 mounted under Kangourou Jouef. The NEM box has been mounted upside down, i.e. facing upwards, to obtain the desired height.

Makette KKK-2 drawbar under Kangourou Jouef

Here is a KKK-1 mounted under Gas Jouef, on which I decreased the distance of the pivots (from 138.5 to 132.5), which is too much compared to the reality (135.1). I had to do it to “fit” the drawbars.

Makette KKK-1 drawbar under Gas Jouef

The problem is that Makette’s are no longer available. AMF87 still offers some, of Huet origin, but they are “compact” models with a short elongation. However, Huet used to offer larger drawbars.

Anyway, even with the Makette KKK-1, I have been confronted with elongation deficiencies, and installation difficulties, for example on the Gas Jouef covered wagon above.

Other drawbacks of the Makette KKK-1: it is not (or very little) adjustable; its mobile arm is fragile, and it is impossible to reinforce it (the Huet is better on this point).

Hence, my idea to try to make a drawbar with a similar design, but with fewer disadvantages: greater elongation, possible adjustment and… availability.

Specifications

This home-designed drawbar should:

Prototype

So, this drawbar is very much inspired by Makette’s and Huet’s, but with a larger “elongation base” — I mean the distance between the two pivot points: 18 mm instead of 12 for the Makette KKK-1 and 14 (at the most, I don’t know the exact value) for the older Huet, allowing a greater elongation.

Here is a study for its implementation on a Gas Jouef wagon.

Drawbar project for Gas Jouef

The coupling system is not shown, but the distance between the drawbars remains 15 mm, regardless of the curve radius, in accordance with NEM 362 (dimension e = 7.5). The buffers, which are extended, do not touch each other in the curve.

Some prototypes were etched with other parts, taking advantage of an order, and mounted on a Jouef Dd4s luggage van being renovated.

Home-designed drawbar mounted on a Jouef luggage van

Click the picture to get a closer view of the drawbar.

On this prototype, there is still a spring hooking tongue at the rear, which increases considerably the space requirement (even though the spring is not tensioned). Furthermore, it is not adjustable in height, but only in length.

Note the fastening with self-tapping P-tite screws, which are very small. A thin double-sided adhesive fastening does not last long. Gluing with CA is possible but problematic if you want to be able to dismantle.

The luggage van has been driven in this way at the head of a train of about ten coaches without any problem.

New model

After learning from the prototype, I designed a new version which is shown below.

New Home-designed drawbar project

The overall dimensions are 18.5 × 22; the length in the axis is 14.5 mm. For comparison, the Makette KKK-1 is 17.5 × 16 (not including the spring hooking tab at the rear).

The notches in the front of the baseplate are used to provide space for the buffer tails that sometimes protrude from the rear of the buffer crossbar. The rear fixing lugs can be cut off if they interfere with the installation. The rear is curved to allow maximum space for a bogie pivot.

The return is made by ø 0,2 bronze or piano wire. This return system has been criticized on some REE wagons, but this was due to poor assembly. It has the advantage of not increasing the length.

However, there is a hole for a coil spring at the rear. It will then be necessary to provide an anchoring point under the vehicle chassis.

This drawbar is adjustable in height (yellow arrow) and length (red arrow). The locking is done by soldering. Once the height has been set, the vertical tongue must be cut back if it could interfere with the dovetail of the NEM coupling head.

Note that, unlike the Makette’s and Huet’s, there are no tabs to secure the three parts of the base. This will be done by the fixing screws, or by lightly soldering the edges.

This new model has not been manufactured yet. I am waiting for a new order to my etcher for that.

Pair of compact
elongating NEM boxes
ref. A185
€6,00 — price 2021
at AMF 87

Self-tapping P-tite screws
for plastics ans resins
ø 1.4 - length 4, 5, 8
€0.15 to 0.18 € each — price 2021
at micro-modele