Power It Up

How to operate & troubleshoot hydraulic & pneumatic tools

Hydraulic and pneumatic tools are essential to almost any major extrication or rescue incident. But these tools are also complex and dangerous, and can easily pose problems to the operator. The best way to mitigate safety hazards and ensure smooth operation of power tools: Know how they operate, how to use them and what to do when something goes wrong. Note: Always consult your manufacturer’s recommendations before operating or troubleshooting hydraulic or pneumatic tools. No recommendation in this article should supercede those of a specific manufacturer. Maintenance (in the field or otherwise) should only be performed by those qualified to do so.

Hydraulic Operating Principles
Hydraulic rescue systems feature five basic components:

• Power unit with a gasoline engine;
• Hydraulic fluid pump/reservoir;
• Associated valves to control direction and pressure;
• Hoses; and
• The tool itself.

While pneumatic, or open, systems vent and consume the power transfer medium, hydraulic systems are closed systems featuring a pressure port (output of the pump) and a return port, so hydraulic fluid flows back into the reservoir. Hoses transmit the pressurized fluid to the tool (spreaders, shears, etc.). Tip: For best operations, hydraulic fluid temperature should remain between 60–140 degrees F.

Pressure is applied in all directions within the hoses, valves and tool actuators. The hydraulic fluid is mostly incompressible but may contain up to 10 percent air. The action that creates the mechanical advantage depends on Pascal’s Law, which explains that a force or pressure on a small surface can be transferred to a larger surface, amplifying the force. Think of the small piston attached to the pump handle of a hydraulic bottle jack. The small force you create by pumping the small piston with the lever (handle) transmits the force (the pressure in psi) to a larger area (the square inches in psi). This is why by simply jacking this pump by hand, you can lift several tons.

Hydraulic tools feature positive displacement pumps, which means that if they pump against a closed head for very long, the pressure will build until something relieves the strain. System operating pressure is directly related to the load applied. It’s ultimately relieved automatically by internal overpressure valves or by decreasing the load on the working end of the tool. Think of a vehicle rescue system ram pushing against a vehicle component. The tool system will load up and build pressure until the object is displaced, the operator releases the tool or the relief valve kicks in.

Hydraulic Safety Issues
Consider the following safety issues when using hydraulic tools:

• Pressures in hydraulic systems can be 2,000–40,000 psi. Always assume they’re  under pressure.
• Treat as “hot” work. Keep a fire extinguisher or charged hoseline nearby.
• Always wear proper personal protective equipment (PPE), including bunker gear and hearing/eye protection.
• When hoses are left in the hot sun or pavement, the fluid will expand and prevent uncoupling. Relieve pressure back through the system.
• Inspect hoses for leaks and excessive wear, ensuring all fasteners are tight. Don’t use your hands to check for pinhole leaks, as the pressurized fluid can penetrate skin.
• Make sure fluid levels are full; do not use any fluid other than manufacturer-recommended fluids.

Most hydraulic units are powered by a small, four-cycle gasoline engine. To ensure operational readiness, start the power unit on each shift. Specific starting instructions can be found in the owner’s manual of your particular tool; however, the following steps work for most units: Pull the choke out full, pull the recoil starter cord, gently allow it to return once the engine is running and return the choke to the open position. Move the hydraulic dump valve to the run position, and cycle the tool to purge air. Start the engine/pump with the dump valve open so the gas engine has no load on it during start-up. Also, keep the dump valve open when changing out tools.

Hydraulic Tool Troubleshooting
Problem: Engine fails to start or is hard
to start.
Possible Reasons/Remedy:

• Out of gas. Check tank and fuel filter/line.
• Spark plug disconnected or faulty. Check and replace.
• Check air filter and plug gap.
• Check crankcase oil level.

Problem: Engine overheats.
Possible Reasons/Remedy:

• Low oil level. Check/add oil.
• Airflow obstructed. Always operate in a well-ventilated area.

Problem: Pistons do not advance.
Possible Reasons/Remedy:

• Low hydraulic fluid. Check and refill if necessary.
• Loose seals or coupling. Check for obstructions/dirt and clean/tighten as needed. If it still leaks, tag it as out of service and send it to a service center.
• Load too heavy. Reduce load.
• Air trapped in system. Cycle the tool full open and closed, keeping an eye on the fluid reservoir level (it may get too low as the air bleeds off as the fluid cycles through the system). Keep in mind that when your tool is fully extended or open, the fluid in the reservoir may appear low, but this is normal. When the unit is off and the tool retracted, the fluid level should return to normal. If it doesn’t, fill as needed with the manufacturer’s recommended fluid.

Pneumatic Operating Principles
Pneumatic tools are lightweight, very portable and have many excellent applications. They create a mechanical advantage just like hydraulic systems.

Air tools, with the exception of air bags, are often measured not only in operating pressure but also in cubic feet per minute (cfm). This is the amount of air the tool uses to work. The speed of the air is expressed as feet per second (fps), similar to the number of amps or the current an electrical tool uses. Cfm and fps can be negatively affected by friction loss in the hoses.

Note: The air in these containers, when static, represents potential energy and must be relieved carefully. Cracking valves or couplings may blow O-rings and launch projectiles.

Drain and charge your pneumatic system by shutting off the source (typically an SCBA cylinder) and opening the control valve or running the tool. Watch your pressure gauges to ensure they bleed into a zero-energy state. To charge the system, assemble it completely, making sure all fittings and connections are tight. Slowly turn on the air source, then adjust the air regulator output to the pressure recommended for your tool.
Our Class D breathing air (SCBA air) will dry out the system’s O-rings and cause premature failure. To prevent this, oil regularly by adding a couple of drops of pneumatic oil into the tool. Extend your usable air supply by jogging your tool to counteract the friction losses in the system. The air consumption of the tool can exceed the regulator and hoses’ ability to deliver the needed cfm, especially when the SCBA bottle is getting low on pressure. It’s not uncommon to find the metal couplings close to the SCBA bottle covered with frost due to the speed of the air moving through the system.

The typical operating pressure for high-pressure air bags is 118 psi. Tools such as chisels can go as high as 300 psi, while others max out at 90–100 psi. For your safety, check the owner’s manual to determine the proper maximum air pressure ratings of your tools.

Key pneumatic tool safety issues: Control bleeding-off of pressure; use a pressure relief valve with air bags; and check the pressure rating of all components.

Pneumatic Equipment Maintenance
Pneumatic tools use specific parts that require correct maintenance.

High-pressure airbags: The airbag will usually have a male air fitting that is rigid and subject to damage (it’s best to keep a couple replacements in your rig’s toolbox). If this fitting is damaged, it usually doesn’t require any type of sealant or Teflon tape to prevent leakage. Instead, the connections are compression fittings, designed to seat together in such a manner that they don’t require additional sealant. This enables us to make field repairs.

Use two wrenches to remove a damaged nipple to prevent damaging the connection to the bag itself. Clean with soapy water; do not use any petroleum products to clean. Fill the bag with 30 psi and check for leaks. If any water gets into the bag, invert and allow to drain. Operate at temperatures between -40–150 degrees F.

Note: High-pressure airbags must be tested quarterly or more often. To test, inflate the bag to 35 psi, hold at this pressure for 10 minutes and apply a soap and water solution to reveal any leaks. If you find a leak around the air inlet connection, bleed off all pressure, remove the fitting, clean the threads, install a new fitting and re-test. If you find a leak anywhere else, it is reason enough to take the bag out of service and return it to the manufacturer for further evaluation.

Pneumatic gun: The only field-repairable part of the gun is usually the retainer ring at the end of the gun. A retainer key is included in most field kits. If the retainer becomes loose, use this key to tighten it back on. Since our application will primarily be powered with Class D air, it’s important to regularly oil the gun. A couple of drops into the air nipple will suffice. This will prevent the internal rubber parts from drying out. When operating in a dusty, damp, abrasive environment, you’ll need to clean the gun regularly. Immerse the air gun vertically in a cleaning solvent to flush out debris.

Only operate the air gun when the bit is firmly against an object. When operated without pressure against the bit, the piston may become jammed or turn the bit into a projectile. Always treat the gun as a loaded weapon, and never point it at anyone.

Pneumatic Tool Troubleshooting
Problem: Piston stops reciprocating.
Possible Reason/Remedy:

• No air pressure or pressure too low. Check supply and hoses for kinks/bends.
• Plugged air holes in valve handle assembly. Visually check for dirt/obstructions and remove.

Problem: Piston stalls; slow operation.
Possible Reason/Remedy:

• Lack of lubrication. Place a couple of drops of pneumatic oil in the air inlet of the tool, then operate the tool to circulate the oil.
• Excessive moisture or lubrication. If you have water coming out of your tool, you need to check your air source and ensure you’re supplying clean, dry air to the tool. If you’re using an air compressor, check its air dryer for proper operation. Once the water is pumped through, re-lubricate. You will know if you have over-oiled if oil leaks out of the tool during operation.
• Worn piston spring. This repair must be made at the service center.

Problem: Loss of power.
Possible Reason/Remedy:

• Air leaks. Check the system with a solution of soapy water, looking for the bubbles to find the leaking component.
• Worn/damaged O-ring seals. Keep spare O-rings on hand and replace as needed.
• Dull tool bit. Ensure your tool bits have a cleaned, dressed edge, free of rust and chips.

Problem: Tool bit stuck in gun.
Possible Reason/Remedy:

• Flange on tool bit is flared. File to repair.
• Tool bit too soft. Check operating pressure for bit.
• Tool bit not being held against work piece when operating. Getting the bit stuck is often caused by not holding the chisel bit against the work piece while operating the tool. Always keep the bit engaged to the work piece (sheet metal, etc.) so the internal piston doesn’t over-extend and jam the bit.
• Air pressure too high. Check the operating manual for the air pressure rating, and don’t exceed it. Adjust the air pressure from the output of your air pressure regulator by turning the “T”-shaped handle.

Hoses
Some hoses are field repairable. If a hose is damaged/cut, use a knife to cut straight down on the hose, creating a square edge. Use pliers to remove the air fittings and ferules by unscrewing clockwise. Where you made the straight cut, replace the air fitting by screwing the ferule back on counterclockwise.

Be sure to check the pressure rating on your hoses. Tool hose found in your neighborhood auto repair facility may only be rated at 100 psi, insufficient for inflating high-pressure bags or working a high-pressure chisel. Make sure all components of your power tool system have a rating capable of its power source.

Air Regulators
Two types of air regulators are used for rescue tools: a diaphragm style and a piston style. The diaphragm style features a larger regulator with a T-handle; it delivers more air than the piston-style regulator. Both regulator types use two pressure gauges; the one on the bottle side reads the pressure in the bottle, and the gauge close to the tool reads the output pressure being sent to the tool through the hose.

Do not assume that an input pressure gauge with a 6,000-psi scale will operate a 4,500-psi source. Every regulator will have its operating pressure stamped on its body. Set the output pressure by adjusting the T-handle or the round knob. This changes the size of the diaphragm, or piston surface area, and adjusts the pressure (Pascal’s Law). If you adjust your pressure too high and want to back it down, you may find that the regulator is not self-venting and the pressure will not drop until it’s relieved through another opening.

Check that the small valve with the arrow is pointed toward the tool; this is the “on” position. The threaded coupling that attaches the regulator to the bottle has an O-ring. Check that it is in place and not broken. Know your tool’s operating pressure so you do not overpower it. When storing the air pressure regulator, turn the air output adjusting knob (T-handle) counterclockwise to remove the pressure from the air regulator diaphragm. This will prevent the flexible diaphragm from deforming over time.

Conclusion
Our ability to sustain hydraulic and pneumatic tool operations in the field will help ensure a positive outcome to extrications and other rescues. Knowledge of how these powerful tools work helps keep our work sites safer. The citizens of your community bought these tools for you with their taxpayer dollars. Not knowing how to use them is simply not an excuse. Get together with your team and train. Learn your stock and trade for a safer and more satisfying service.

Steve Shupert is a lieutenant with the Miami Township (Ohio) Fire/EMS Department. A 17-year firefighter/paramedic, Shupert works on the second platoon Engine-Rescue Company 48. He is a member of the Ohio Task Force 1, and was task force leader at the World Trade Center and during Hurricane Katrina. He is also a member of the FEMA/USAR Rescue Working Group. Shupert was FireRescue’s 2006 Company Officer of the Year.