Sunday, 17 March 2013

Project Heavy Haulage: Update 4

I had started to have a few doubts about Project Heavy Haulage, mainly because of a few details which I thought were wrong. So, I decided to take a few steps back and get the truck back on the right track. My main concern was over the chassis length: European trucks are only as long as they need to be because of legislation and the general need to save room in towns, depots and ferries, and the Volvo’s chassis had become unnecessarily long when I converted it into a 6x4 (see this post). I decided that the chassis needed a reason to be long, and what better reason than an extra axle? Also, I realised that the cylindrical diesel tank supplied in the kit was outdated and not right for my truck, so I decided to make a square tank which would fit into the space left between the axles.  This meant removing the diesel tank and battery box I had previously installed.
Several small companies make conversion kits to enable truck modellers to add extra axles, and add new diesel tanks. However, I decided to do some research and make my own new parts. First job was to make an extra axle: I decided to make a lift axle (an extra axle which can be dropped down onto the road to allow the truck to carry more weight, then lifted after the job to save on tyre wear and improve cornering) as these seem to be common on heavy haulage trucks. This was created starting with a spare steering axle complete with steering mechanism, onto which a frame was made out of plastic L-beams to mimic a real lift axle frame I found online.

Real lift axles use airbags to raise and lower the axle: I made a pair of airbags out of Milliput (epoxy modelling putty) and stuck them onto the frame. After a coat of grey paint to match the truck chassis, the lift axle was installed using superglue. I will need to add some mudguards for the wheels, though I am not sure whether to make some or buy a pair from a resin parts manufacturer.
Adding the lift axle meant there was not enough room for the cylindrical diesel tank which came with the kit, and which was inaccurate and outdated anyway. So, I decided to make a modern square tank to fit the space (heavy haulage trucks often seem to have odd-sized diesel tanks). My main concern was weight: truck diesel tanks are notoriously difficult to attach to the chassis because they are big and heavy but only attach via a couple of small brackets. To help overcome this, I decided to make my new tank out of balsa wood which is a nice lightweight building material. After measuring the space the tank needed to fit into, I cut several pieces of balsa wood to the required size and glued them together using PVA glue.
After letting it dry for a few hours, I sanded the balsa block to shape and gave it a layer of Squadron Green putty to begin to make a smooth finish. A few coats of putty were required before the block began to look smooth enough for painting. After all, it needed to look as smooth as metal when finished so it was very important to smooth over the grain of the balsa wood.
After a few coats of putty, smoothing each layer with sandpaper between coats, the diesel tank began to take shape and was then sprayed with several coats of satin black enamel paint to prepare it for a coat of Alclad chrome lacquer. The Alclad will give a natural metal finish like a real diesel tank.
I also did some more work on the crane, which will be mounted behind the cab. I completed assembly and added the decals, and I also added some hydraulic lines which were missing from the kit (these were made from black sprue heated in a candle flame and stretched to the correct thickness). I then applied a black oil paint wash to highlight the details and add a grubby, used look to the crane. I will talk more about washes in a future post: they are easy to do and can add a very realistic look to your model.
Next jobs on Project Heavy Haulage: finish the diesel tank. Add the crane and cab details.

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