I need to replace the porous hoses that run from the hydraulic pump to the turret. Doubtless they are some weird US thread dating from the 80s. I'll need to remove them to replace them obviously but I also need to determine what couplings they have used.
Firstly, let's uncouple the hoses at the turret end. Access is tricky!
What is the coupling? Well it's clearly 19 TPI. That's a pitch of about 1.34mm ie not 1.25mm or 1.5mm, so unlikely to be any form of metric thread. That isn't surprising given that this machine hails from the USA in the early 80s. The only thread I can find that uses 19TPI is the British Standard Pipe thread, which comes in parallel (BSPP) or tapered (BSPT) forms, depending if it's to be jammed into a hole or used with a hose coupling.
For reference, the taper plugs I bought to block the holes in the manifold recently were 1/4" NPT. However, the nearest NPT thread is either 18 or 20 TPI, so it's not one of those.
Naturally, the hoses on the Tree also have a male (convex) cone on the male couplings and a female (concave) cone on the female couplings. Whereas the std BSPP males have a female (convex) cone and the BSPP females have a male (convex) cone.
The turret hoses are each 3m, whereas the long coolant hose is 6m long. To keep things simple, I've ordered 4 of the 3m long hoses and will join 2 lengths together for the coolant with BSPP / BSPP straight adaptors.