Our tractor  had two spool valves - these are the valves that control hydraulic cylinders on machinery attached to the tractor.

Two services  or spool valves always seemed enough for everything that we needed. When we bought the tractor the only thing we had that needed two spool valves was the loader. But when we bought a bale grab we found that there weren't enough holes to connect all the hoses to!

This is the valve block at the rear of the tractor, to use a tipping trailer one spool is fine - because the weight of the trailer lowers the hydraulic ram.

But with other implements you need double valves or spools.

A double acting spool can push the hydraulic piston up and pull it back down again

 To get a 3rd service I bought an electrically operated hydraulic diverter valve which I fitted in the "Crowd" ram circuit. The diverter valve is activated  from a push button switch, via a relay, on the second lever in the cab, when I press the button the solenoid diverts the hydraulic oil to the cylinder in the this case the ram on the bale grab and when I release the button it allows the oil back to "Crowd" rams so I can angle the bale grab.

 One of the companies that make 6 port electric diverters are the Walvoil Group  - I don't think they sell direct to the public.

I used a Walvoil model DFE 10-6-003 which costs about £110 this came from T. Cook Ltd, Agrispares (Devon) 01837 810230

The finished installation with all the cables and wires tie-wrapped up out of the way, inset photo shows the button used to switch to the third service which would be used for the bale grab or a dung grab. Tiny button from RS Components part number 265-0629  cost about £ 6.00. I also used a  12 volt solenoid between the switch and the hydraulic diverter valve. There were various hydraulic pipes to be made up. I tried to use as much of the existing pipe work as possible.