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R3171 P2 Speedo Drive attachment ?


Colin Ayres

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Whilst you wait for a reply, perhaps you would spend a few minutes reviewing the TIPs in the TIP page link below:

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TIP: As a newbie poster on the forum, just be aware that the 'Blue Button with the White Arrow' is not a 'Reply to this post' button. If you want to reply to any of the posts, scroll down and write your reply in the reply text box at the bottom of the page and click the Green 'Reply' button.

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See also – further TIPs on how to get the best user experience from this forum.

https://www.hornby.com/uk-en/forum/tips-on-using-the-forum/

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I have had a close look at pictures of the prototype and the Hornby models and cannot see anything resembling a speedo drive attached to the wheel cranks. 

 

There appears to be what is likely to be a lubricator off the centre drivers and various other rocking links to the valve gear but nothing else that rotates with the wheels.

 

Maybe if you posted a close up picture of the errant part as dangling we could help more.

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Thank you everybody for your replies. Picture attached. Have seen the part advertised as a spare ' speedo drive ' , as stated I'm still stumped, unless the plastic part above has lost a rear retaining point/ lug /media/tinymce_upload/59bcbf2edbce31e1fef6b437f109ed5e.JPGto allow it to spin ?

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The joggled crank arm secured by the driver bolt should have a slot in it to keep it rotating such that the open hole is stationary about a point, giving the impression the crank is turning something about that point. The speedo 'gearbox shaft' should locate to this hole probably by way of a (missing) spigot. 

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I think it is part of the Caprotti valve gear. Is it on the front drive wheel. If so isn't there an identical part on the other side. 

 

Think back to Ken's live P2 steamer project where he made a similar such thing into a working shaft either side of the loco.

Rotary Poppet Valve, spoken to on page 1 near the bottom.

Worth a read of the whole project but there is a picture here of the prototype...

https://www.hornby.com/uk-en/forum/post/view/topic_id/25633/?p=6

 

 

 

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Images of the cylinder block/valvegear assembly X6647 show there is a circular protrusion on the inside of the square black plastic moulding (covered on the outside by the representation of the circular bearing cover) which appears to be intended to locate in to the circular hole in the crank, which as Rob says, should stay in one position rather than rotate.  By applying pressure between tweezer jaws, the metal and plastic components should come back together.  If a crank is rotating, it may not be positioned correctly under the crankpin screw head or the screw has been tightened too much.

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That definitely looks to me like the drive for the Caprotti valve gear. I have no idea why it would be disconnected. I can't lay my hands on my P2 just at the moment.

 

Just poor alignment of the plastic bits with the drive gear. Maybe gentle manipulation would better align them.

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