What would this be for?

[Classic3CX]

Does anyone know what this is for on the back actor, or whether something is missing from it?

[essexpete]

At a guess it is where you would check and fill for the gear oil in the slew rack. It may perhaps incorporate a breather?

[agrimax]

Spot on pete. Drain bung underneath on the big round plate. Probably be mostly water and gunge that'll run out.Unscrew the filler/breather(which incidently should have a cap on the top of it) and refill with HP 90 gear oil.(or whatever heavy gear oil comes to hand for that matter)

Edit...Forgot to say around 4.3l to refill.

[gecko.cx]

Mine looked the same - if there should have been a cap to keep water out, mine was also missing it.
When I drained the slew box, I got 1.5L of nasty water and nothing else.
I couldn't get the plug out without destroying it (didn't seem a big loss!). I then fitted a poly plug which I'd drilled to take a cheap fuel filter. A short length of hose inverted at the top will hopefully keep water out for the future

[Classic3CX]

Makes sense now, thanks for the replies. I shall have a look at draining it one day soon to see what comes out!

[Classic3CX]

Wondering if this would be suitable for the application

[agrimax]

That'll work fine.As long as there is something fairly viscous and lubricating in it,that's the main thing!