Titanic's Reciprocating Engines



Hi, there

A question about the telescopic device attached on top of each connection rod (see attached picture)

What's the purpose of this device?

In some posts on this forum, it was mentioned as being surely a kind of telescopic pump used for lubrication of the crosshead pin.

But I don't thing so.

My understanding is that device is used for indicating the steam engine when setting adjustments have to be applied on the reverse gears or for other performance tests of the engine.

The end motion of the telescopic link close to the Y frame, is replicating, at a smaller scale, the true displacement of the piston during his stroke.

And during indicating measurements, each ends of these telescopic links are connected by mean of a cord to one indicating device installed close to each cylinder.

On the second here attached picture, we can see an another equivalent telescopic device used on SS Jeremiah, specialy made and added during indicating this triple expansion steam engine.

Link to the video from wich this picture was extracted is HERE

Is my analysis correct?


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Tim Aldrich

Tim Aldrich

It's an oil tube. The triangular bit on the left end is an oil cup that would be refilled as necessary.


Hello Jim,

Thanks for yor answer.

That's what I thought also at first sight, and what also seen on few other 3D modeling of this engine, as the one here attached.

Now, I've some doubt on those device.

It seams that each cylinder has two telescopic devices attached to the side of their connecting rod pins

This connection is made on a thin bracket bolted to the side and under of the connecting rod pin witch can't be, from my point of view, used to pass oil in thru and lubricate the pin brasses.

I've attached a detail of this connection from a 3D drawing made here by Cian O' Relly for a better understanding.

It should be more simple to connect a swivel joint directly in the center of the connecting rod pin if intention was to lubricate this part with such kind of device.

And the triangular bit at the end of the telescopic device, close to the Y frame is very small for me and can't be an oil cup if the telescopic device is expected to be an oil pump.

From my point of view it may be something different.

The picture I've attached in my previous conversation is related to the Britannic engines and was taken during shop ass'y.

But the assembly where not fully finalized when the picture was taken, and so may be some others part connected to the end of theses devices where not still in place.

I've seen on several videos made on SS Jeremiah O'Brian and as well on SS John W. Brown, very similar devices installed. Both are Liberty Ships

They are on those vessels installed also on each Y frame and attached to the connecting rod pin of each cylinder, but are used as simple mechanical actuator to drive other oil lubricators

And these oil lubricators seams to be dedicated to cylinder and valves lubrication.

Lubrication of their connecting rod pin brasses are made by gravity by means of oil cups attached to them.

Here attached some anotated pictures from SS Jeremiah O'Brian and SS John W. Brown

What do thing about this proposal ?


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This picture found in the "Media section and posted by @etan oliver HERE seems more correct regarding lubrication of the connecting rods.

But what's the purpose of these two telescopic devices attached to the crosshead ?
Cian O'Reilly

Cian O'Reilly


This picture found in the "Media section and posted by @etan oliver HERE seems more correct regarding lubrication of the connecting rods.

But what's the purpose of these two telescopic devices attached to the crosshead ?
Hi Jude, thanks for your continued interest! One thing to note, I haven't yet added any of the lubrication lines to either the piston rods or con-rods, or to the valve gear, so right now those details are missing. They will be added when I can get the time to dive back in to the build. Any info or thought you provide are greatly appreciated as this is anarea the remains quite mysterious to me.


Hello Cian,

Thanks for your answer.

I know that your awesome modeling is not yet finalized and it's not a problem for me.

I'm just very interested by construction details of these engines which are unfortunatlely very difficult to find as no many available documents and it's why I've asked several technical questions here in your tread.

For example I can't understand what's the purpose of the 2 telescopic devices attached to each crosshead.

Did you have any idea ?