Air Products Zeibig trailer

Some time ago whilst travelling along a motorway I passed an unusual looking trailer, it was an Air Products outfit and was loaded with gas cylinders but not in the style usually seen on delivery trucks, either laying down or standing in cages but these were standing upright in regimented rows the full length of the trailer.

I thought to myself that could be an interesting subject to model and put it to the rear of my list of things to do, but curiosity got the better of me and I contacted Air Products to find out something about it, after several phone calls I reached the right person in Air Products and they advised me the trailer I saw was what they call internally, a “Zeibig” It is their standard trailer for transporting Hydrogen gas around Europe, they have approx 100 of these vehicles and it's been in production for approx 14 years. I was amazed to learn that these cylinders are not unloaded at the customer’s premises as you would expect, instead the trailer is left connected to the house line at the customer’s facility until empty, the tractor unit then returns and takes away the empty trailer and returns it for refilling back at Air Products depot.

When I mentioned to Air Products I was interested in building such a model and would they help me, after clearing it internally, they kindly provided me with a selection of GA drawings, photographs and technical advice as and when I needed it.

I am partial to a bit of scratch building like the odd container tank etc. etc. but the more I looked at this I realised I had bitten off a little more than I could chew, nil desperandum, I was not going to let this beat me so I sorted out my material requirements and worked out some build plans.

The chassis was the first item so the drawings were enlarged to 1/ 24^th scale and sheet plastic was cut for the frame webs I used 60thou card for this as it had to be strong and 40thou for the edge flanges and reinforcing sections. The cross members were cut from Plastruct fine line styrene square and rectangular tubing plus some strips . The running gear came from a revell fridge trailer but KFS do a similar running suspension, it was simply cut off the bottom of the moulded frame and cemented onto the new chassis frame .

The legs were from various square tubes with Revell feet and winding gear box . I chose KFS resin wheels, super singles, these come with the tyres and hubs but these hubs are not the correct ones for the trailer so I cut the hubs from the Revell/Italeri wheels which are correct and they fit the revell axles without further modifications, The hubs were fixed to the resin wheels using epoxy resin to make sure the union was strong enough to take the load.

I chose the super single mudguards from M&G who also supplied the airline connectors, the stays were cut lengths of TB2 Plastruct rod which has brass wire for its centre giving a good strong item. I read in TMW Howard’s idea for adding mudguards with a small jig so I made one to fit this trailer but once marked up and the holes drilled out the guards were removed until all was painted

There is a structure at the front and rear of the trailer which act as a headboard and tailgate both these have strong cables from mounts near the top to points on the inside of chassis and are safety measures in case of collisions. Each is made up from Fineline styrene rectangular tubes and sheet plastic, these are bolted to the chassis so I used the hexagonal rod from Plastruct to represent the bolts, just tiny slices cut off and placed in position with the tip of a scalpel blade, only the front one was mounted permanently at the beginning to give a starting point for the load .

Various boxes at the rear and the brake control panel on the chassis side were constructed from 20thou sheet and plastic angles, a mount was fitted ready for the fire extinguisher, the rear bumper and light fittings were made up from styrene “C” channel. I tried my spares box for the correct tail lights but no luck so they were shaped out of 80thou card then painted with Humbrol #11 silver and when this was dry it was over coated with Tamiya clear red and orange for the flashers

<>Under run bars along the sides were built up from strip and square rod, with TB2 rod supports which were bent to fit the drawings then a bracket was added to one of these to take the red document canister which each trailer carries.

With the trailer almost complete it was time to start on the load, the cylinders are mounted upside down on a “corrugated” metal pallet with rows of holes and rubber collars which they stand in, these I had vacuformed from a simple wooden master and while waiting for these to be made I made a start on the cylinders. I had a choice of manufacturing them, either cast in resin or made up using Plastruct tubing, the resin would have been too heavy for the chassis and so I went the Plastruct road even these weighed in at 2.2Kilos.

There are 296 cylinders on the trailer so I needed 600 end caps for the tubes just to give me a few spares so I telephoned the nice lady at EMA model supplies and asked how many she had in stock, she replied plenty until I mentioned I needed 600 but she took my order and the items were shipped from the USA Plastruct in about a week, now began the tedious bit, several times I wondered why I had started this.

Using my mitre box I sawed 300 pieces of tube all to the same length and to each of these I cemented two end caps then each of the joins were sanded smooth. This took a couple of weeks as one could only do around 30 at a time before cramp set in these old fingers.

On the real cylinders every other one has two rubber ring spacers to stop cylinders rubbing together so on half the number I used evergreen 2mm strip to represent these and some slices of smaller tube were cemented to the bottom to represent the collars, I used these to adjust the height of each one later by sanding to the overall length of the cylinders.
Painting was next in the order of things; the chassis was sprayed with humbrol #3 dark green and the pallets were sprayed silver #11. The cylinders needed an undercoat to cover the grey plastic so I used Humbrol #130 satin white before a final gloss white coat was added . All the spacers and collars were given a coat of Humbrol #85 satin black and the edges of the pallets or raves had the corporate orange and green colours masked and sprayed.
A big problem was how to mount 296 cylinders in neat level rows on five separate pallets keeping them upright; I made a small jig to mount individuals but that wasn’t too good so I made a jig to make up a row at a time and this worked well, each pallet has eight rows of eight cylinders.

The first pallet has the first row empty but it can be filled if extra capacity is needed, each row was then cemented to the pallet and a dab of superglue was also placed on the “rubber” spacers. When the first pallet was filled I turned to the bracing to hold the lot in position, these are two U shaped bars along the top corners of the cylinders, cables anchor these to the pallet In a cross and vertical manner. I made the bars using Fine line deep channel and at the exact locations I inserted a triangular section of 30thou card, drilled at the three corners to take the telephone wire “Cables”. The cables were cut to just over the required length and one end of each was attached to the appropriate hole, the bars were then placed roughly in position and the side to side cables hooked into the opposite hole then the vertical cables were fed into the predrilled holes at the base. Once everything lined up the cables were tensioned up and the ends bent over to lock them in position.

Around each group of cylinders there are retaining straps which are adjusted with ratchet tensioners and are placed in such a fashion that each group is locked into another, a sign that Air Products take safety matters very seriously. I ordered the ratchets from KFS but Howard was unable to supply the correct colour straps so it was off to the nearest haberdashery shop to find the right colour, white. These were used in a slightly different manner to those on a curtainsider; the strap was fastened to the ratchet, passed around the cylinders and back into the ratchet for tightening, the strap was pulled through but not fastened yet and to make sure the straps were all level a tiny dab of superglue was placed under each turn at a corner and the tension checked until I got back to the ratchet where it was fully tightened and superglued, A final Cut left a half inch protruding this was then treated with superglue to stiffen it and hold it in position. As you can see in the photos the straps are in specific places and at three levels so particular care was needed to place each one in its exact location, I found the strapping was stiff enough to be inserted between the assembled cylinders making it one of the final things to do.

The Pallets are loaded on to the chassis now, one at a time, and when all are mounted the rear structure can be placed in position and the final straps can be fitted. To make sure all the top bars were level a short length of square rod was cemented into the rear end on each bar with half of it protruding so it would locate the next one exactly. The raves were made from a rectangle tube which had been cut in half along the narrow edges making two C channels, after it had been painted I inscribed lines to represent the ends of each pallet thereby keeping it as one piece to ensure that it also was straight and level

There are a number of Hazchem signs on the vehicle and it would be expensive to have decals made for these so I tried another method which worked very well, I had photos from all around the vehicle covering these so I used “photoshop” on the computer to resize all the items including the number plates, various warning signs and even the mud flaps these were then arranged into a 6X4 photo in the right quantities and printed on proper photo paper. When the photo had dried the back of it was covered with double sided tape and each item was cut out and stuck onto 10 thou plasticard, trimmed up and mounted in the appropriate position and if needed the rear was painted in the correct colour. The mud flaps were just tacked on with a thin strip of the tape.

The large company logos on the sides and rear are cut vinyl laid onto 30thou white plasticard cut to size and then coated with Johnsons Klear to seal everything in.

The unit was an Italeri Mercedes kit built out of the box with a few alterations such as the addition of a fire extinguisher mounted on the side of the chassis. The stripes around the cab were home made decals, the two colours were sprayed onto experts choice decal paper in broad bands then coated with Microscale Decal film when dry strips were cut to size and applied The names were done on the computer and printed onto the same paper.

All the air lines and electrical cables were made from various telephone cables and fitted to the unit; later the vehicle was fitted to the base of a display case and then covered to keep out any dust that might accumulate.

I started with doubts on this project but it gives me a great satisfaction now I see it finished.

Ted Taylor

Jan 2008