Tyfon Maintenance
A typical Tyfon horn is constructed rather very simply. Basically, it comes with a bell, a diaphragm, and a back cap, with the bell, diaphragm housing, mounting foot, and nozzle together as one unit. The back cap can be adjusted, and just like WABCo's E-2 or the Nathan M horn, can be fastened securely. Most, if not all A-75s and some A-125s, as well a few A-200s, are made of bronze material. There are A-125s and A-200s that are made out of aluminum. Rarely, you may stumble upon an A-200 that is made of cast iron!
Assembling a Tyfon horn is quite easy. Normally, this is done by by placing firmly the diaphragm into its housing and then fastening it to the back cap. The horn is then voiced, and the locking bolt (which is a boltwith a square head ) on the diaphragm housing is tightened. The housing must not be bent too much, however. You may avoid this tendency by placing one or two washers between the two ears of the locking bolt.
On the other hand, disassembling the horn requires skill and caution. To separate the parts of the horn, the locking nut which is secured by a cotter pin on the diaphragm housing must be loosened. Then, while blowing air into the horn, the back cap must be unfastened. With the parts now separated, check the nozzle and the internal seat, making sure that they are level with one another.
Next, look at the diaphragm closely. Diaphragms may be made of metal or plastic, while some may be rubber-coated. If the diaphragm is made of metal, its curved side must face the nozzle, while the leaf that is least used pressed against the nozzle. This is to put pressure against the nozzle, and will enable the diaphragm to move back and forth. If you are working with a plastic diaphragm or a rubber-coated diaphragm, keep in mind that it has a step on one of its sides, specifically one that is facing the nozzle. This is to form a seal against the nozzle, allowing the diaphragm to oscillate.
Regardless of the type of diaphragm you are dealing with, remember to have it replaced if you notice any cracks, deformities or anything unusual. Remember, too, that it is fairly common for rubber-coated diaphragms to assume a different direction after some time. At any rate, when that happens, you will need to replace it.
After checking the diaphragm as well as the nozzle, you will now need to assemble the horn and voicing it. In order to do this, you must remove the diaphragm and put the back cap all the way again. The back cap has to go in easily. If you encounter any kind of tension while you doing this, check the threads and make the necessary adjustments. Then, insert the diaphragm once more, followed by the back cap. Next, with 10 pounds below the normal operating pressure, tighten the back cap until you are satisfied with the sound it produced. When all that's done, tighten the lock nut further, and then test the horn again, this time using full pressure. If it does not sound music to your ears, you may need to readjust the back cap.
