TO: All maintenance personnel. FROM: The Fluid Power Safety Institute™. SUBJECT: Lock and block - it could save your life! A diesel mechanic, with no hydraulic experience, was severely injured as a result of an accident he suffered while replacing a hydraulic hose assembly on a front-end loader. He was found crushed between the machine's lift-arm assembly and the front axle. The accident occurred while he was replacing a defective hose that transports oil from the directional control valve to the closed-end of the bucket roll-back cylinder. Preface - Here is a typical layout of the front frame assembly of an articulated front-end loader. It consists of a frame, bucket, lift-arm assembly, lift-arm cylinders, bucket roll-back cylinders, and axle assembly. What he did to prepare the machine for the work - The victim rolled the bucket forward until the edge of the bucket was more or less at right angles to the ground. This gave him the access he needed to reach the hose connector at the closed-end of the roll-back cylinder. The closed directional control valve blocked the oil in the cylinder and prevented the bucket from moving. He also set the machine's park brake. What kept the bucket from moving? - When the front-end loader's directional control valve is in the neutral position, it traps the oil on both sides of the cylinder piston and prevents it from moving. In addition, the bucket lip is planted "firmly" in the ground and the park brake is set. Nothing can move! What caused the accident? - The victim apparently failed to realize that if he disconnected the hose from the cylinder, it would allow the oil to escape leaving the piston free to move. In addition, he evidently failed to realize that once the cylinder "lock" - the oil, was removed, it left the bucket free to move. He also failed to take two additional factors into consideration: the geometry of the bucket relative to the lift-arms and roll-back mechanism, and gravity. The moment he removed the hose connection at the closed-end of the cylinder and allowed the oil to escape, the lift-arm assembly collapsed crushing the victim between the lift-arms and the axle. Two factors contributed to or caused this accident: 1. The victim had no training in hydraulics, therefore he did not realize that the forces of "oil," a cylinder piston, and a closed valve, "locked" the cylinder and prevented it from moving. 2. He assumed that the bucket would remain in position when he removed the hose connection from the closed-end of the roll-back cylinder. How can this type of accident be prevented? - 1. Training is the most effective tool for preventing accidents. People who are properly trained are empowered to make safety-based decisions. 2. Take EVERY precaution possible to prevent unexpected movement of any type of mechanism. Use proper blocks, and place them in the proper position(s) to prevent crush injuries. If you are not sure ask! 3. The word "ASSUME" belongs in the safety arena from one point-of-view only: ASSUME THE WORST! Assume if you don't lock a machine out it is going to start unexpectedly! Assume if a machine is not properly blocked it is going to move! Assume that if you don't work safely you are going to get hurt! 4. Have the safety department compose a "bullet-proof" Job Safety Breakdown" (JSB) for this task. Don’t leave critical blocking procedures to the discretion of service and repair personnel. 5. Discuss the blocking policies and procedures with the appropriate personnel in your safety meetings - plan ahead! 6. Don't reinvent the wheel! Contact the machine manufacturer, or refer to the correct service manual (serial number of machine must match serial number marked on service manual) for information about correctly blocking a machine. 7. If all else fails, follow these guidelines (these are guidelines only. YOU MUST OBTAIN MACHINE SPECIFIC INFORMATION FROM THE MANUFACTURER). Here are suggestions on how to make an articulated front-end loader safe to work on: CAUTION: These are suggestions ONLY. Obtain "machine-specific" instructions from the machine manufacturer. 1. Park the machine on a flat surface. 2. If the machine is articulated, install the front/rear frame steering locking arm. 3. Roll the bucket forward as far as it will travel and rest the cutting lip firmly on the ground. 4. Place the bucket control lever in the "hold" position. 5. Apply the park brake. 6. Turn off the ignition and remove the key from the keylock switch. Fasten a tag to the steering wheel indicating that the machine is locked out for repairs. WARNING! Follow your company's prescribed lockout procedures. 7. If the machine is equipped with a steering system accumulator(s) follow the machine manufacturer's recommendations for safe accumulator de-energization and verification. 8. Place suitable chocks at the front and rear of all wheels. 9. Disconnect the battery cable or set the master switch and remove the key. 10. Place the manufacturer's lift-arm lock(s) in place (if available). If unavailable, block the lift-arm assembly with suitable stands or blocks. DO NOT climb under the machine to install the blocks! 11. Do not suspend the lift-arms with a cable, chain or an overhead crane. THE ASSEMBLY MUST BE BLOCKED! (Unless otherwise stated by the manufacturer). 12. De-energize the hydraulic energy and verify de-energization before loosening or removing any connectors. 13. Wear safety glasses when working on and around hydraulic systems. WARNING! Upon completion of the work it may be necessary to start the engine and air-bleed the cylinder. DO NOT climb under the lift-arm and bucket assembly while the engine is running. Install a closed-loop air-bleed system on the cylinder to facilitate safe air-bleeding. 14. If a cylinder has been replaced, DO NOT start the engine and climb under the machine to install cylinder retaining pins. Use a portable pump to extend/retract cylinders for alignment purposes. 15. Upon completion of the work, start the engine, operate the hydraulic system, and check for leaks. If there is a leak, and it is necessary to climb under the lift-arm assembly to gain access to the leaking connector(s), replace all necessary blocks. DO NOT tighten a leaking connector while it is under pressure. If the connector fails, it will allow the oil to discharge at high velocity. The oil can be hot enough to cause severe burns. It could also penetrate the skin. Skin penetration of hydraulic oil can result in severe injury or death.

Waiver of Liability -

The Fluid Power Safety Institute™ does everything possible to ensure that the information and drawings contained in this safety notice are accurate, and the suggested procedures are deemed safe and reliable. However, these are general recommendations only and might not be applicable to all situations. You MUST have your engineering department in conjunction with your safety department read these recommendations and make the necessary changes for your application. The Fluid Power Safety Institute™ is not responsible for actions taken by untrained and/or unauthorized persons. Trained, authorized persons only should do ALL fluid power system service, repair, and troubleshooting.