VODL/SC Series - Aluminium body - Steel bodied units available on request - add suffix AC This valve controls a moving load in both directions preventing it from moving ahead of the pump and locks the load in any position on U1 and U2. It also provides static overload and thermal expansion protection when used in combination with an open centre spool valve. This valve permits free flow from D1 to U1 & D2 to U2 and blocks the flow from U1 to D1 & U2 to D2 until a pilot pressure generated at D1 or D2 is sufficient to pilot the U1 or U2 port open.