Is it ok to engage/disengage the lathe slide nuts while it's moving?

[123hotchef]

In its centre position it allows you to use the half nuts for threading. If you move it up or down you engage the surfacing or facing feeds. I can't remember which is which. Bu its easy enough to work out.

Thank you I am sure @bR39Da had a play with them when he had a visit

 

[Wedg1e]

In its centre position it allows you to use the half nuts for threading. If you move it up or down you engage the surfacing or facing feeds. I can't remember which is which. Bu its easy enough to work out.

Aye, good point: when the lever's in either sliding or surfacing you can't engage screwcutting, and if you use the halfnuts it locks out the other option
Up is sliding, or traverse, down is surfacing, or cross-feed.
As a further complication, if you use the tumble-reverse lever you can make it power-feed left to right or back to front, rather than the other way around
Sometimes surfacing from the centre outwards is preferable, especially with a roughly cut part/ intermittently-cutting tool - less likely to dislodge the workpiece from the chuck (especially if it's tube).

 

[Wedg1e]

It's a Colchester Student 6", circa 1930s

The engagement lever is just a solid lever, that can be engaged/disengaged and can switch between slide and surface. These images from lathes.co.uk seems pretty accurate:

View attachment 281329

View attachment 281330

Aye, that predates the Mk2 version where there was only one lever but also a push-pull knob above it which selected sliding or surfacing - the lever had the trip adjustment as a twist-grip arrangement. I'm not sure how your version is adjusted for trip pressure though, sorry.