The circuits show three examples for redundancy in load-holding applications with counterbalance valves.
- Load-sensitive counterbalance: CB**, CW**,CA**
- Vented pilot-to-open check : CV*V, CK*V
- Pilot-to-open check with bypass orifice: CN*E
Benefits of this circuit arrangement:
- Fig.1 includes a vented pilot-to-open check valve on the cylinder.
- A 3:1 pilot ratio is the only available option and can only be installed on the full bore side as shown. This is a solution where regulations prevent springs being used to keep cylinders in position.
- Fig. 2 includes a pilot-to-open check below the CBV. Since there is no pressure build up between the two valves, the P.O. check valve can open at a low pressure. The orifice across the P.O. check valve limits the cylinder speed if the CBV upstream fails.
- Fig.3 offers redundancy with two CBVs in series. The valve upstream is a vented CBV with a high pilot ratio and will open first. The second CBV ( lower pilot ratio ) will then open and control the cylinder speed.
For Sun technical support, contact Steve Weber.
