Lift

This section allows guests to comment or ask questions. Posts from guests require explicit approval (which generally takes a day or so), before they appear, so that we can prevent unwanted spam.
Stanier6256

Lift

Postby Stanier6256 » Thu Jan 22, 2015 8:45 pm

Grosvenor asks what is meant by 'lift'.

A steam locomotive has balance weights fitted to the driving wheels to balance out some of the fore and aft forces from the cylinders. Only a portion of this force is balanced (you will see why shortly) and the result of balancing a rotating body in this way transfers the amount of force balanced into an equivalent force at right angles to the horizontal plane. This force will cause the weight on the drivers to be reduced (and increased) twice per rev and if the rotational speed is high enough that force will reduce the load on that set of wheels sufficiently to cause it to rise off the rails. I witnessed some tests at St Rollox in 1951 on an LMS 8F 2-8-0 which was being rebalanced (remember the famous 'stars')to allow it to run at passenger speeds and we lodged it against two locos with their brakes on, greased the rails, and ran the loco up till the wheels just lifted off the rail surfaces which established a speed which should not be exceeded in service. I can't now recall what that speed was but it was well above anything an 8F would ever travel at.

Alistair Wright
ScR CME's pupil 1951

Return to “Guest Book”

Who is online

Users browsing this forum: ClaudeBot and 0 guests