Titanic's Portside Engine - Part 1

Written by Robert Hahn

built by Karl-Friedrich Pohlmann

Like anywhere else, here in model building are modelers with different skills. Some build plastic kits, while others make scrachtbuilt models. The following model is an example of the very best model building I have seen, especially for Titanic. It is Karl-Friedrich Pohlmann's 1:20 scale working model of Titanic's portside engine. Mr. Pohlmann lives in Germany and concentrates his interest on old steam and internal combustion engines. He also did a model of one of the engines of the well-known German liner Deutschland, which may be presented in a later issue of the Docking Bridge. Actually, he is working on an 8-cylinder aircraft engine of the early 1900's.

Now, back to Titanic.

Figure 1 shows the beautiful profile of the inboard side of the engine, which faced the centerline of the hull. Figure 2 shows the outboard side, the side that faced the side of the hull. You can see nearly all of the detail, which will be described below.

Fig. 1: The beautiful engine from the starboard (inboard) side, which faced the centerline of the hull.

Fig. 2: The engine from the port (outboard) side, which faced to the side of the hull

Figure 3 shows a view from the forward end, or that part of the engine that faced the bow, and shows a pulley with which the model is turned during display at shows and model fairs. When actually run, the engine will run on steam, but to avoid corrosion in the cylinders and pipes, only compressed air is used.

Fig. 3: Forward end of the engine.

In June 1996, after his model of the portside engine of the Deutschland was completed, Mr. Pohlmann started the research for his new project. The only resources Mr. Pohlmann had available were the various books, with which most of us are familiar, containing pictures of the engines in the workshop of Harland & Wolff, and the drawings of the engines printed in The Shipbuilder. As you may know, those plans are only basic drawings, intended to show the arrangement of the machinery rather than any detail of the engines themselves. Mr. Pohlmann tried to contact Harland & Wolff for assistance, but unfortunately they were uncooperative. This is sad, because as you see this was a serious project. I hope that the people at H&W read this and will be more cooperative in the future. Due to the lack of detailed drawings, Mr. Pohlmann had to improvise in some cases, especially for the small pumps and auxiliary engines. Here his immense knowledge about old steam engines was very helpful and he did an incredible job.

Cylinder, Bedplate and Columns
First Mr. Pohlmann created new drawings for some of the engines parts by measuring out the plans. He began with the bedplate, the eight ‘Y’ columns and the cylinder casings. All of these parts were made as aluminum castings. For these, wooden patterns had to be fabricated first. Figure 4 shows all parts after being cast and taking out of the molds, prior to any finished machining.

Fig. 4: Bedplate, columns and cylinder cases after casting

The eight columns required extensive machine work after casting, to make sure, that all four cylinders could be mounted parallel to each other. The guides for the cross heads inside the columns were made of bronze and screwed in.

The cylinders are fitted with sleeves made of cast iron, because the pistons are made of aluminum too as well as the cylinders. As some may know aluminum on aluminum is not a very good combination for proper sliding, like aluminum on cast iron is. After this, the steam holes in the cylinders were milled and the 168 (!) threaded holes for the cylinder head bolts were drilled and tapped in.

The eight webs of the crankshaft were cut by laser and then precision-drilled. The completed built-up crankshaft and the bearings and bearing keepers are shown bedded in bedplate in figure 5.

Fig. 5: Bedplate with crankshaft and bearings

Cylinder heads
Figure 6 shows the cylinder cover of the low pressure cylinder at the front with the main engine stop and throttle valve and the high-pressure cylinder right behind. The cylinder heads are made of cast iron. On top of the cylinder cover you can see the piston tail rod coming out of the cover, as it does on each of the other cylinders as well (see figure 1, 2 and 3).

Fig. 6: Cylinder cover of the low-pressure cylinder with the main valve

Unfortunally this arrangement is not correct for Titanics engine. The reason for it is the lack of information and missed support from Harland&Wolff. Mr. Pohlmann told me he though to see it in pictures of the wreck and for the steam valve of the high pressure cylinder he is right, but not for the cylinders themselve. Anyway it was a common arrangement for steam engines in those days and this was the reason, why he made the decission to construct it that way.

Reversing Gear
The reversing gear was used to change the direction of engine rotation, thereby change the ship’s direction of travel from ahead to astern. The engine uses a reversing engine of the Brown’s type, shown in figure 7, which through a series of linkage actuates the wyper shaft, the horizontal silver shaft seen running the length of the engine beneath the cylinders in figure 2. The four bell cranks - the reversing arms - visible on this shaft control a series of linkages under each cylinder that changes which eccentrics (ahead or astern) operate the valves controlling the admission and exhaust of steam for each cylinder; the links for each cylinder are shifted simultaneously. In figure 7 you can see the cylinder, which contains a steam-actuated piston. Moving the lever seen to the right of the cylinder changes the position of the piston. The piston moves the two vertical silver rods, which move the linkage controlling the wyper shaft.

Fig. 7: Reversing gear

Turning Engine
The turning engine, shown in figure 8, was used to turn the crankshaft of the main engine in order to bring the engine’s moving parts into the position required during repairs and inspection. It was also used to slowly turn the engine during the warm-up process that was performed prior getting under weigh. When the main engines were not under steam, as when in port, the turning engines were also use to change the position of the main engines a little each day to keep the moving parts in good working order.

To turn the engine, the vertically oriented shaft fitted with the worm gear was swung to the left to put the worm gear in contact with the main toothed wheel. After this the two small cylinders, fed by steam, turned the vertical shaft, thereby turning the crankshaft of the main engine. The model needs 45 seconds for a complete 360° turn. Their full-sized counterparts were required to be able turn the main engines through one complete revolution every eight to ten minutes.

Fig. 8: Turning engine

In the next issue of the Docking Bridge, part 2 of this article will describe the thrust block and many more wonderful details of this model steam engine. If you have questions regarding the model, please send them to me, I will forward them to Mr. Pohlmann. Send your mail to Hahn@titanic-model.com.

Robert Hahn