MECH ANIC ’S CORNER ◗ EDDie konrad
Hydraulic Safety ◗ In the last GreenMaster, I wrote about force and motion to familiarize you with Pascal’s Law. Pascal’s Law states that pressure applied to a confined fluid at any point is transmitted, undiminished, throughout the fluid in all directions and acts upon every part of the confining vessel at right angles to its interior surfaces and equally upon equal areas. Let us do some in-depth examination of how this can apply to our jobs as equipment managers. Hydraulic circuits and components used in turf equipment include gear pumps, spool valves, gear motors, and hydrostatic systems. In order to make hydraulics work for us, we need hydraulic fluid, a motor to drive a pump, a reservoir containing hydraulic fluid, a filter to continuously clean this fluid, a cooler or heat exchanger to prevent the fluid from overheating and pipes or hoses to build hydraulic circuits. The purpose of the fluid we are using is to cool internal parts, transfer power, lubricate moving parts and carry contamination to the filter. Most of our equipment uses hydrostatic transmissions because it makes things simpler. There are no gears or clutches and the transmissions are easy to install and can be operated with a single lever control or pedal. Therefore, hydrostatic transmissions have a faster response than other transmissions and we can use the system for dynamic breaking and rapid reversals, which increases maneuverability. Since hydraulic systems must store fluid under high pressure, three kinds of hazards exist: burns from the hot, high pressure spray of fluid; bruises, cuts or abrasions from flailing hydraulic lines; and injection of fluid into the skin. Important safety measures include the proper coupling of high and low pressure hydraulic components, having pressure relief valves and conducting general maintenance. Once a person acquires a thorough understanding of hydraulic safety, the principles and laws that govern hydraulics, the purpose of the primary components in a hydraulic system and, finally, the theoryof-operation of hydraulic components, he/ she is ready to advance to learning and 40 greenMaster | www.golfsupers.com
Porta power attachment
understanding diagnostics. One fact that is commonly overlooked is that double-acting, single rod hydraulic cylinders, which are used to a great extent on our equipment, not only provides the means to lift heavy loads, but is also a device which converts fluid energy into linear mechanical energy which makes it a pressure and flow “intensifier.” Looking at the cylinder’s rod-to-bore ratio of 2:1, meaning that the major area of the cylinder piston is 10 square inches and the rod area is 5 square inches, Pascal’s Law tells us the following: because we have 3000 PSI pressure in an area of 10 square inch (Force = Pressure x Area) the force created is 30000 lbs. If the area is reduced to 5 square inches, (Pressure = Force ÷ Area) then the 3000 PSI 10 inch pressure is intensified to 6,000 PSI (414 bar). Anything
example of a Cylinder rod-to-bore ratio
not withstanding this pressure becomes a safety hazard. Pressure intensification is shown with two gauges on a lift cylinder. The main area shows 2400lb and the minor area shows 3000lb. The major area is 12.5 square inches and the minor area is 10 square inches. Pressure = 2400, Area = 12.5, Force = 30000, Minor area is 10, Pressure = 3000. Operating a portable, hand-operated, high-pressure pump, commonly known as a porta-power, without a proper pressure gauge can cause severe injury. This portapower is attached to a ram via a high pressure, flexible, rubber hose. Using the porta-power to pump high pressure oil into the ram to press a bearing into its housing could cause the threaded connector, attaching the hose to the porta-power, to unexpectedly fail. This means you will never know what the pressure was before, or at the time of, the failure when you are sprayed with oil or hit by the flailing hose. The forces generated by a porta-power and its attachments can be extraordinarily high. Thus, it is imperative, for the sake of safety, that personnel using a porta-power, and its