Door-Hinge Design


Door-Hinge Design

TOPIC: Understanding Door-Hinge Design and Effective Door-Removal Techniques

OBJECTIVE: Given a vehicle door that is opened and required to be removed from a crash-damaged vehicle, the rescuer will recognize the specific door-hinge design and employ the most effective tactics for door removal.

TASK: The rescue team shall study the fundamental door-hinge designs and develop effective techniques for each when given the assignment for door removal at the hinges.

Rescue teams have been opening jammed doors at crash scenes for a long time. Completely removing the door once it is opened is another common extrication task that many times follows the opening of a jammed door. An essential element of being competent in completing these two door tasks is for rescue personnel to be able to understand what style door-hinge assembly they are dealing with. Once the door-hinge design is understood, then an effective technique for door removal can be implemented. Some techniques work better for a specific hinge design than others.

Vehicle door hinges can be roughly grouped into two categories of hinge designs. One we will call the "C" hinge and the other style, the solid hinge. Call them what you want in your department; it really doesn't matter. What does matter is that you recognize what style you are confronted with at a crash scene and use the most effective tools and procedure for removing the door.

For our purposes, we'll call any hinge that is shaped like the letter "C" as our "C" hinge. These can be short or tall hinges and can consist of thick metal or be relatively thin designs. The full hinge assembly would look like two "C" hinges facing each other with a steel pin holding them together. If you simulate this hinge design by forming the letter "C" with your hand, then your fingers represent the top of the hinge and the bottom of the hinge is represented by your thumb. Your fingers are what we will call the top "leaf" of the hinge and your thumb represents the bottom leaf. We'll talk about attacking the top or bottom leaf of a hinge in a moment.

The other common door-hinge design uses solid metal elements to join the door to the car. They may be thick cast or stamped metal with a steel pin joining the hinge sections together. We'll call this design the solid hinge style.

For each of these hinge designs, the rescue crew should have a Plan A for how they want to attack the hinge assembly to completely remove the door. For the "C" hinge, removal options include forcing the hinge unit apart with a spreader tool or cutting the hinge. If spreading is your Plan A choice, then you can either place the tips of the spreader tool near the hinge or possibly inside the "C" hinge itself. When this author employs a spreader to break the door off the car, the "top of the top; bottom of the bottom" procedure is used. With this easy-to-remember process, the spreader tips are placed above the top of the top hinge and operated just until that hinge fails and comes free. Then the spreader is repositioned to the bottom of the bottom door hinge. With force applied low in this area, the door generally levels up. When the bottom hinge fails, the door will come free. Operating a spreader high on the edge of the door for too long may actually drive the lower corner of door right into the ground. A careless tool operator can go so far as to begin to lift that side of the car. This is all avoidable.

If cutting either style hinge with a power cutter is the Plan-A technique to be used, then the tool operator must know whether the size and thickness of the metal making up the "C" or solid design hinge is able to be cut with their tool. A cutter that is not powerful enough when put up against a big hinge that consists of thick metal, may stall out. You have to realize that if you intend to have your cutter bite through the entire hinge at one time, then it has to be powerful enough to cut through double the thickness of metal that you see. This is because many times, the "C" hinge crushes as the cutter closes, making a double layer of steel hinge to cut through. If confronted with a "C" hinge for example and you are doubtful that your cutter can do the job, angle the cutter down from the top and place one blade of the cutter into the hinge so you cut just the top leaf of the top hinge all by itself. Then make a second cut that severs the bottom leaf of the same hinge. Making two cuts per hinge is not a waste of time if the job gets done. A less-than-powerful cutter that tries to bite through both leaves of a big "C" hinge for example might stall as the hinge crushes together but doesn't cut. You should not put yourself in the position of having your cutter stall out because the hinge squeezed together and exceeded the capability of your cutter.

For late-model vehicles, prepare yourself to deal with cutting through or breaking the door retainer strap or linkage once the hinges are cut. This assembly will be somewhere between the top and bottom door hinge. In addition, you will also have to deal with the thick power cables, referred to as the "umbilical" cord. It will take more than a pair of paramedic shears to cut through some of the larger, thicker umbilical cords on vehicles today. Be prepared for this. The tool operator should have a hand tool with them to cut through the umbilical if they are not using a power cutter to take the door off in the first place.

Rescue teams should closely study door-hinge designs during their next extrication training session. Knowing what tools you have in your inventory and what techniques work best for the "C" hinge and the solid hinge will make for more efficient operations at real-world incidents.

TASK: The rescue team shall study the fundamental door-hinge designs and develop effective techniques for each when given the assignment for door removal at the hinges.

RON MOORE, a Firehouse® contributing editor, is training chief for the McKinney, TX, Fire Department. He also authors a monthly online article in the "MembersZone" and serves as the Forum Moderator for the extrication section of the website. Moore can be contacted directly at