Knuckle couplers have been used on real railroads since the 1880's. They mate automatically in the open position and uncoupling is done by moving a lever on the end of the car. Although this is very simple, model railroad couplers have a far greater variety of designs. They fall into three basic categories:
1. Dummy Couplers- These have no moving parts. They do not couple or uncouple automatically and are basically used for looks not operation. To uncouple you must actually lift the car off the track.
2. Nonscale Automatic Couplers- These are furnished in most train sets and plastic kit sets. They bear little resemblance to the real thing. The HO horn hook couplers rely on side pressure to keep the couplers mated. They couple automatically when cars are pushed together. There are a few companies that offer magnetic couplers which allow easy coupling and uncoupling without manual labor. Other than poor appearance the main disadvantage of the horn hook design is that the side pressure of couplers pushes the car ends when backing, often causing them to derail.
3. Semi-scale Automatic Couplers- These are a combination of the two. They have a modified working knuckle. The knuckle is held in a closed position by a spring pressure or gravity. An uncoupling is accomplished by stopping them over a magnetic field. These couplers are both more effective and realistic looking.
Insuring Smooth Operation- In order for your couplers to run smoothly here are a few ideas which you should follow:
*Couplers should be free of paint.
*Lightly lubricate each coupler pocket with graphite.
*Make sure there are no rough edges on the couplers.
Coupler Height- Good coupling depends on proper positioning. The couplers must be the right height in order to help you insure your couplers are the correct height, use the following chart:
Scale
Standard Height
Actual Height
O
11/16"
.718"
HO
25/64"
.397"
N
.216"
.216"
If a coupler is too high you can place a shim between the coupler pocket and the car floor. If it's too low, you can either cut away the under frame or add washers between the truck bolster and the car body. You also must make sure the trip pin height is correct. If the trip pin hangs too low it will sag in your track work, and if its too high it won't uncouple.
Conversions- Converting your pike from one type of coupler to another is very difficult. Many manufacturers sell conversion kits and provide instructions to help. Make sure when you're converting that you make a few cars that have an old end on one side and a new end on the other. This way you will be able to use both new and old couplers.
