Tim “The Toolman” Taylor glamorized the use of tools on TV's “Home Improvement” in the 1990s. Tools are one of the mainstays of the electrical industry. Talk to just about anyone involved in construction and they'll be able to tell you what a pair of dikes are, what a hickey is or what a crimper is. But ask someone about LPHT and you may get a “deer in the headlights” look in return.
LPHT, or low-pressure hydraulic tools, have been around for quite a while but are not as well known as their counterparts. In general, tools are classified by the method of power transmission to the work area. They can be mechanical (engines, belts, pulleys or ratchets), electrical (batteries or electric motors) or fluid power (hydraulics or pneumatics). In the case of LPHT, the fluid power hydraulic oil circulates through a tool circuit at about 3 to 8 gallons per minute (gpm) and 1,000 to 2,000 pounds per sq. in. (psi) — quite a departure from the typical 10,000-psi at which a high-pressure hand-held hydraulic crimper operates.
Low-pressure hydraulic tools are connected via hydraulic hoses and HTMA (Hydraulic Tools Manufacturers Association) couplings to a power source. A variety of power sources are available, including gasoline/diesel hydraulic power packs (may be as compact and lightweight as a 5 hp unit), hydraulic tool circuits on bucket trucks or perhaps a power take-off (PTO) from a service vehicle.
An important distinction between tools is whether the hydraulic power source you are using is “open center” or “closed center.” The open-center system allows a continuous flow of oil through the tool while the closed-center system prevents the flow of oil from running through the tool until actuation. You need to make sure that your open-center LPHT tool is run on an open-center hydraulic circuit and vice versa. It is easy to switch tools that have dual-action spools between open- and closed-center settings. Finally, you should always test the gpm and the psi of the tool circuit to prevent possible seal damage to the tools. Test kits are available that measure gpm, psi and oil temperature.
LPHT tools are used throughout the utility, construction, railroad, tree care and public works sectors. For the utility and construction markets, tools available can include impact wrenches, chain saws, circular saws, breakers and water/trash pumps. Saws can be hand-held or can be mounted on dielectrically-rated fiberglass poles. The water pumps typically have a discharge rate of up to 750 gpm (gallons per minute) and are submersible and self-priming. Applications in the utility market may involve utility pole installation and maintenance, breaking and cutting concrete, tree trimming and water removal from vaults.
The beauty of LPHT tools is their simplicity of controls, ergonomic designs and high power-to-weight ratio, which makes them extremely efficient. One manufacturer's tools incorporate a Gerotor motor, which has gears that turn in the same direction. This results in less friction, less heat, less wear and slower speeds yet higher torque. Slower speeds translate to greater safety and longer-lasting accessories such as augers, blades and saw chains. Several manufacturers offer anti-vibration handles on models such as breakers. Features such as “engaged reversibility” allow the user of an impact wrench to toggle under power between forward and reverse, making it a snap to remove rusty or corroded hardware. The same feature when combined with a 12-in. plus long auger makes it quite easy to bore through a utility pole and reverse.
Having seen the variety of LPHT tools that are available, I've noticed that if either electrical or pneumatic output is desired, both LPHT-powered electrical generators and air compressors are offered. Contractors may wish to use an existing low-pressure hydraulic circuit to power a high-pressure hydraulic tool. In this case, manufacturers offer a series of internal or external hydraulic intensifiers to convert the low-pressure flow input into high-pressure flow output for use with remote crimping heads and cutters. The intensifier system being used will generally accommodate either single-acting or double-acting tools and may require single- or double-acting hand controls. The difference between single and double acting is that a spring is used to retract the ram or piston in single-acting tools while hydraulic flow is used to retract the ram or piston in double-acting tools.
The final components of the LPHT system are the hydraulic hoses and couplers. Hoses and whips are available as either conductive or non-conductive. HTMA “dripless” couplers are preferable to standard couplers. As the name implies, dripless means a cleaner working environment.
Low-pressure hydraulic tools may not be as well known as their high-pressure brethren, but their wide variety, superb performance and durability make them tools that you should consider.
Paul A. Werthman is the western division director of FCI Burndy Products.
LPHT Do's and Don'ts
DO make sure that the hydraulic hoses are hooked up to the correct “in” and “out” ports. The tool and the power source will have in and out markings to guide you.
DO confirm that you have ordered the appropriate male or female couplings to complete the power source to hose to tool installation.
DO insist on using non-conductive hoses and dielectrically-rated poles where a shock hazard is present. Before use, wipe the length of the hose and fittings with a clean dry absorbent cloth.
DO read and follow the manufacturer's safety and operating instructions. Always have safety equipment readily available including eye protection, ear protection and gloves.
DO order the necessary accessories with your LPHT tools. Remember saw blades, augers, sockets, discharge hoses, mechanical adapters and grinders.
DON'T connect or disconnect a tool while the hydraulic power source is running. Hydraulic fluid can get hot.
DON'T run the tool above or below the manufacturers' specifications for flow/pressure and backpressure. Running the tool below specifications can cause the tool to under-perform and running the above flow/pressure specifications can damage the tool.
DON'T check for hydraulic leaks with your hands or allow a hydraulic hose to become “kinked” or bent backwards 180 deg.