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Keeping fluid power out of court

Many machines powered by fluid power systems possess the potential for dangerous - even fatal - accidents. The most effective safeguard against such accidents may be simply to warn operators what can happen if they don't follow instructions, render safety devices inoperative, or remove them

Our legal system originated with English common law, but the status of product liability legislation in the United States continues to change with new decisions and rulings. The most significant change took place in the 1960s in the Greenman vs Yuba Power Products decision, which created strict liability in tort (wrongful act) for dangerously defective products that harm human beings. This resulted in greater responsibility for manufacturers that produce products that may cause injury if defective.

Because national tort reform bills have failed in Congress the past several years, manufacturers must design and conform to 50 separate state jurisdictions with varying laws and decisions regarding the interpretation of strict liability law. Many local courts have additional rulings and statutes that make defending your design decisions and actions difficult. Some states do not have a statute of repose (cessation of all legal activity), so manufacturers must consider that lawsuits could originate over the life of the machine. Additionally, juries tend to be made up of non-technical people who find expert testimony confusing and many times decide for the injured party because they have been given two totally opposing views of a product's safety and performance. The burden of due care lies with the manufacturer of a product, and actions that may have been considered contributory negligence in the past may be disregarded and a large judgment rendered if it is proven that defective products were designed, manufactured, or labeled incorrectly.

Failure to warn

Many plaintiff's attorneys seem to concentrate on failure to warn because most people can judge if a warning is adequate to them, whereas technical issues are more clouded. A debate currently raging in product liability litigation addresses warnings and safety signs that are not effective and of little value. However, ANSI Standard Z535.4 clearly exists for product safety signs, and both SAE and ASAE Standards call out descriptions and specifications for product safety signs.

Designers should be familiar with these and other standards that pertain to their industry to avoid suits that allege failure to warn. It is commonly considered among plaintiff's attorneys that if a company does not conform to all applicable standards for their products, they have a very difficult position to defend. This encourages attorneys to represent clients on a contingency basis; they may not be interested in such cases if the warnings were adequate and conformed to standards.

Designing for safety

When first defending our company in product liability cases, I was disappointed to find that courts may hold a defendant to a higher standard of due care than current industry standards require. Having someone in your company follow the progress of litigation in this area is very helpful and could keep your company at the forefront of your industry in conforming to and developing a safe environment for your customers.

The generally accepted order of design safety is:

1. Eliminate the hazard and/or risk
2. Apply safeguarding technology
3. Use safety signs
4. Train and instruct
5. Prescribe personal protection.

Both legal and engineering safety consultants may be needed to establish whether your company has conformed to this order adequately. We have an engineering and legal consultant who advises our companies regularly on product liability issues. A safety policy for all company personnel to follow also ensures that you develop new products and hydraulic circuits with safety concerns first.

Protection for all

Guards and shields, which protect operators, mechanics, and casual by-standers, should be permanent if possible. They should be required to be in place to operate the machine or at least carry safety signs warning against operation without them being in place. Signs may need to be under a guard and should be shown in the operator's manual. Safety signs under guards should also carry the information requiring the guard be replaced and how to obtain a new guard and operator's manual.

It is a good policy to include a periodic procedure in the operator's in structions to clean all safety signs, along with how to clean the surface before applying replacement signs. Consult your legal experts concerning if you should place safety signs both under a removable guard and on the guard if removal causes a hazard.

Hydraulics cases

There are cases that exclude hydraulic component parts manufacturers from liability because someone misapplied a properly designed and manufactured part. These cases usually require that the manufacturer not know the details of the application, and that they were not asked to judge if the machine was safe as designed. If a machine manufacturer does ask a manufacturer of a hydraulic component if their machine's design is safe, and the component manufacturer offers either correct or incorrect advice, then a transfer of responsibility occurs if the advisor is considered an expert.Ý

ÝChildress vs Gresen Manufacturing Co., U.S. Court of Appeals, Sixth Circuit, Oct 31, 1989.

Two recent cases involving hydraulic equipment have resulted in large judgments for injured parties because the manufacturer warned operators of the hazards of the hydraulic device only in the operator's manual rather than on the machine itself.

One injured party claimed that a delimber continued to freewheel or drift when left in an upright position with the power off. The operator lost his arm and was awarded $1.5 million plus an out of court settlement with another defendant. The operator knew a safety chain was missing but did not know how dangerous the machine was without it.

Inadequate warnings on the machine were the basis of the case against the manufacturer.ÝÝ

ÝÝLawrence vs Equipments Denis, Inc., Oregon, Multinomah County Circuit Court, July 27, 1993.

The other injured party was attempting to repair a malfunctioning lead extruder machine by bleeding the hydraulic cylinder. The procedure was outlined only in the operator's manual, which was not available to him. A partial manual he consulted did not contain the proper procedure. He was injured when highly pressurized hydraulic fluid was injected into his thumb. The suit was based on strict liability for failure to warn. The Minnesota Court of Appeals found that
(1) the defendant should have foreseen its machine would be operated by workers who were not fully trained in its maintenance and repair, and
(2) the dangers associated with the process were not obvious to such workers. The plaintiff's attorney alleged that the defendant had breached its duty by failing to place a warning on the outside of the machine.*

*Krutsch vs Walter H. Collin GmBh, Verfahrenstechnik Und Maschinenfabric, Minnesota Court of Appeals, 1993.

Warning label shows potential danger graphically and in text.

A sample safety sign, shown at left, can be attached to high-pressure products warning of fluid injection safety hazards. One purpose of the sign is to educate those involved with the equipment and to aid in treating any injuries.

This brings us to the general conclusions about the trends we have in the United States concerning product liability and manufacturing design, care, and responsibility:

* technology has outdistanced common knowledge
* safety of operators, mechanics and bystanders - both during foreseeable misuse and intended use - must be of primary concern when designing products, guards, and safety signs, and
* the trend continues toward corporate and individual responsibility for strict liability, regardless of the manufacturer's exercise of due care.

Based upon these facts, we should all be very much aware of the necessity of safety considerations when designing products and systems. 

A case history

Failures often occur as the ultimate result of a progression of events. Such was the case with the failure of a hydraulic hose on city refuse trucks. The first of 100 trucks was delivered to the user as part of a contract. A new electronic shifting system had been incorporated into the hydraulic system. A solid-state program and solenoid valves without manual overrides had been tested and approved for the application.

The system was powered by an aluminum 25-gpm pump driven directly from the vehicle's power takeoff. A filter rated for 20 gpm with a paper element was installed in the system. When metal contamination jammed the valve spool after several weeks, the hydraulic oil severely heated when personnel attempted to operate the truck.

The hot oil heated the main pressure hose under the truck and softened the tube within the thermoplastic hose. The hose released from its fitting and sprayed the truck's catalytic converter with hydraulic oil, starting a fire. The truck burned and almost set two nearby homes afire.

A second truck burned in the city's maintenance garage and almost caught that building on fire. It was determined that the manufacturer had:

* provided inadequate filtration
* made no provision for manual override if the valve failed, and
* supplied a hose with improper temperature tolerance if a valve failed.

Needless to say, the manufacturer had a large insurance claim.

Failure to adequately warn

Proving to a jury that a defendant did not adequately warn an operator of the potential dangers of a machine is usually the easiest route for a plaintiff's attorney to take in a lawsuit. To help avoid such litigation, follow these procedures:

* keep copies of design blueprints permanently
* form a design group to study the potential uses and misuses of the machine or circuit
* design or select each component in the circuit so that its failure will not cause other components to fail
* study and address a list of "what ifs" so that the safest components are used
* if you cannot reduce risks to a safe level, pursue a different or new design
* designing out risks is better than guarding or warning against them, and
* consider each safety suggestion and document reasons if it is not implemented.

Follow industry standards that address warnings on equipment to help avoid accidents and liability. While no standards guarantee safety, ignoring them could make you an easy target for liability. Standards often used in fluid power equipment are available from SAE International, the American Society of Agricultural Engineers, and ANSI, which is the highest standard in the U. S.

You should also consider following the Factory Mutual Product Safety Sign and Label System.

Color of labels is also important, and is endorsed by ANSI Z535.4. Follow these guidelines:

* red signifies danger - immediate hazards that will result in severe personal injury or death
* orange signifies warning - hazards or unsafe practices that could result in severe personal injury or death, and
* yellow signifies caution - hazards or unsafe practices that could result in minor personal injury or product or property damage.

In many cases, your best recourse may be to design your own sign or modify a standard warning or sign. When doing so, be sure to evaluate the format of the sign and have the sign tested for recognition. Keep all pertinent records in a permanent file.

Access to disassemble systems under pressure

* Shield access to accumulator fittings, and warn against disassembly under pressure conditions.
* Shield access to fittings, hose, tubing, and valves that may cause a load to fall on the person disassembling the component.
* Design safety valves to prevent a load from dropping on someone attempting to move valves or disassemble the hydraulic system.
* Specify detents for remote valve actuation to avoid accidental lowering of loads; this is an OSHA code on dump trucks.
* Attempt to have the load always in sight of the operator when lowering.
* Require double actuation of electrical switches to ensure safe lowering and avoid accidental actuation - use recessed pushbuttons or toggles.


Warren Hinzie is sales & marketing manager of Energy Mfg., Monticello, Iowa. He manages product liability defense for Energy Hydraulics. This discussion is provided for general information and should not be relied upon by you or your company because it may not be suitable for your particular business. The information contained herein, if implemented, could be harmful to your company under certain circumstances. Consult with counsel skilled in product liability for specific information or advice.