Car Door Locks Opened Quickly With Air Chisel
Releasing auto door latches, designed to withstand a load of 4000 pounds or more, is a quick and simple operation with a compressed-air chisel, we have found in the Middletown, N.Y., Division of Fire.
The air chisel we use is specifically designed for rescue work. It operates with air regulated at 225 psi that is taken from breathing apparatus cylinders. There are different designs on the market, but I prefer the cutting chisel that moves freely in the chuck and will rotate 360 degrees.
The first step in releasing a front door is to cut about a 12-inch-square hole just below the door handle. This exposes the safety lock assembly. Now you can reach in and try to release the safety lock assembly. If you can’t release the latch, you will have to do more cutting.
The exact spot to cut the hole varies slightly on front doors of different makes of cars. On the rear doors of many cars, the safety lock assembly is above the door handle.
In a typical General Motors safety lock assembly, only two pins (or rivets) are visible on the outer side, Figure 1. This is what you would see looking through the hole in the door if the control rods and other devices were removed. The inner workings of the latch assembly are underneath the cover.
On all GM vehicles, cutting through the top pin should release the lock. You have to insert an air-operated chisel through the assembly casing to make the cut, but it should take only a few seconds to sever the pin.
In Figures 2 and 3, the cover has been removed to show how the safety lock assembly operates. We will call part A the latch lock and part B, the latch. In Figure 2, the latch is in the down position, the normal position when door is closed. The latch lock (A) holds the latch in this position and prevents it from going to the open position.
In Figure 3, the latch assembly is in the open position, the normal position when door is open. Note the position of part A and part B. Once the latch lock (A) is raised, it will automatically release the latch (B). It is this simple mechanical action that helps the latch assembly to withstand a load in excess of 4000 pounds before releasing.
Quickly With Air Chisel
As previously explained, when the pin that holds part A in position is cut, part B (the latch) will automatically release.
Figure 4 shows a comparison between the GM safety lock assembly and the one used on Ford Motor Company cars. Although Ford uses a different design, the same principle applies. However, on Ford Motor Company cars, the bottom pin must be cut to release the safety lock. Note that the Ford safety lock does not have a cover.
The side of the latch assembly that is exposed on the outside of the door is shown in Figure 5. This latch is in the locked position.
A Ford Motor Company latch in the open position is pictured in Figure 6.
A Chrysler Corporation safety lock assembly is shown in Figure 7. The top pin is the one that should be cut. Remember that the pin must be cut inside the assembly through the side of the casing or an opening on top of the assembly.
Figure 8 shows the safety lock assembly with the cover removed. Part A, the latch lock prevents part B, the latch, from being released. When the pin indicated is severed, the latch will move freely.
We have discussed the safety locks used by the Big Three. The American Motors lock is basically the same as the others, but it probably more closely resembles the Chrysler lock assembly. As with the others, the latch can be released by cutting the top pin.
The more you practice, the better you become, and I have found the best way to practice is to ask junk dealers or body shop owners if you can bring in your equipment and cut up a few doors. I have found these people most willing to cooperate.