Tech Tips - Forget Hydraulics

Sponsored by Page 15 MORE USEFUL IDEAS For Using Air/Oil Tanks (continued) Bi-Directional, Two-Speed Stop & Hold Here’s another helpful circuit showing double Air-Oil Tanks used with shut-off valves & needle valves to provide: (1) Stop & hold in either direction at any point in cylinder travel. (2) Choice of rapid or control rate in either direction at any point of cylinder travel. Figure 13 - Bi-directional, 2-speed, stop & hold Figure 17 - Fabco-Air Single tank construction highlighting the engineered baffle system TIPS FOR INSTALLING AIR-OIL SYSTEMS 1. The best control is achieved by installing the speed control valves so that the fluid being forced out of the cylinder is being controlled. 2. The piping between the cylinder and the speed controlling valve should be rigid enough to maintain the required rigidity of the system. 3. It is best to mount the tanks so that the bottoms of the tanks are higher than the cylinder. Cylinder ports should be up with piping running as straight as possible to the tanks. This aids in purging the cylinder of air, by allowing the air to rise through the piping and into the tank where it will dissipate. Monitoring fluid through the translucent fiberglass 1. The highest fluid level should be kept reasonably near the top baffle to avoid excessive air usage, providing the quickest cycle reversal, and to allow for possible fluid loss. 2. If the fluid levels in the tanks become unbalanced, the fluid is bypassing the cylinder’s piston seal. This can occur in a new cylinder with U-Cups designed for air service or side loading on the piston rod. In old systems the bypass can be a result of seal and cylinder wear, seal shrinkage, or other reasons. A crossover valve can allow for fluid level balancing. (See Figure 12) 3. Fluid aeration and foaming can reduce intended cylinder control and make its operation “mushy.” Properly designed air-oil tanks have special baffling top and bottom which eliminates such disturbance (Figure 17.) Fill Port Flow Port Custommolded Buna-N tube seal Usable Oil Capacity Flow Port Drain Port Brass baffle plates, tube, & spacers, top& bottom Quiet zone belowbaffle plate for sediment to settle out Translucent fiberglass tube Baffles force fluid or air to sides of tank, eliminating surface disturbance, aeration & foaming