31 Jul Hydraulics : Elegant Muscle part 4
By Steve Loutrel
The functions of a control system include choosing which cylinder to adjust, reading the pressure in the selected cylinder, and increasing or reducing the pressure.
Cylinder control systems come in various packages. The simplest is the integral cylinder, which has the cylinder, pump, reservoir, release valve, relief valve, and gauge built into one self-contained assembly. In rigging applications it can be simply substituted for a turnbuckle. (The stay may have to be shortened; some builders use a longer turnbuckle designed to match the length of the integral.)
One step up from the integral is the single-function panel that controls one cylinder. The panel may be mounted just about anywhere on deck or below; remote pressure/force displays are best installed in easy-to-read locations. A single-function panel consists of a pump, gauge, relief valve, and release valve. It is connected to the cylinder and a nearby reservoir.
The next level is to add a selector valve, allowing the same panel to control up to four cylinders. As it has only a single gauge and relief valve, only the selected cylinder has its pressure displayed; when pumping, the relief valve protects only that cylinder.
The top-level control system is a multi-function, multi-valve configuration. This panel typically has a single two-speed pump with a separate high-flow valve assembly for each cylinder or function. Each high-flow valve has a gauge, a relief valve, a pump/hold/release valve, and a flow-control valve to control the speed of release. The valve is designed so that the knob position indicates whether it is the pump, hold, or release mode.
A large racing yacht may have a number of control panels, either independent or interconnected in various ways. For example, it can be possible to adjust boomvang pressure from several different panels. For additional speed, multiple pumps can be trained on a single function.
Stephen “Steve” Loutrel is Consultant in Naval Architecture and Mechanical Engineer
Director of engineering in Navtec and Lewmar-Navtec from 1976 to 2009