And now, a word from our sponsor, the Van Dorn Coupler Company, excerpted from an article printed in the August 12, 1905, issue of Street Railway Journal.
Some Experiences with Draw-Bars for Electric Cars
by W.T. Van Dorn
The real action of the present form of Van Dorn automatic coupler is probably but little understood even by its users. Figs. 1 , 2 and 3 have been prepared showing sections through the 1902 form of coupler. Fig. l shows the position of the link and coupler heads after a coupling has been completed. In Fig. 2 the couplers are shown in the process of coupling. Fig. 3 is a vertical section through the same coupler, Figs. 1 and 2 being horizontal sections. The first thing to notice is that in Figs. l and 2 the link has been inserted in the righthand coupler and fixed by the center pin which has been dropped through the link. The point of the link that is inserted into the head is held in position by the abutment block, as shown, and the part of the link that projects out is in position for automatic coupling with the opposite head. When the cars come together the point of the link will strike the pin that is against the side wall. The link is deflected past the pin and comes in contact with springs in the side of the drawhead, which are forced out until the point of the hook passes the pin. It is readily seen from Fig. 2 that with a link having an elongated point sufficient in length so that when the strain sideways is brought to bear, the point of the link on the spring is close to where the springs fulcrum in the side wall of the draw-bar; the link under no conditions can be twisted out in train service, no matter what the strain may be.
The design of a link to prevent the uncoupling of cars under all conditions has been a matter of much thought. Previous to 1902, a form of link was used with shorter points, and when they became badly worn they could be accidentally disengaged on the shove, although they served their purpose admirably in the work which draw-bars were called upon to perform at that time. The 1902 pattern was designed to prevent any possibility of trouble with the unusual strains of the multiple-unit system. All Van Dorn draw-bars are now made of the pattern shown.
The tight coupling with little lost motion, before mentioned as such an important matter, is made possible by the present design of coupler, which is such that the essential dimensions—that is, the location of the holes with reference to the coupler faces and the dimensions of the links, can be made a matter of accurate machine work.
A coupler having once been made accurately, it is next in order to inquire what are the chances that, after the wear of years, it will remain reasonably accurate. The wearing points are evidently the coupler faces, the pin holes and the hooks on the link. In the first place each coupling head had two pin holes, and that insures double the wear. Each link is automatic at each end. Place the bar in either head and the pin through the center aperture and couple automatically to the opposite head (the wear on pins is only on the pull and not on the shove), and the wear is only on the two pin holes that are in operation at this time. Place the bar in the opposite head and it is vice versa; and that assures double the life of both coupling heads and coupling bar. The coupling bar is made out of the best quality of steel forgings, and after years of wear can be readily upset to a standard length. One of the greatest features of the Van Dorn couplings is their great durability and the possibility of making them as good as new with a very slight cost, and of their maintaining a tight lock over a long period of years.
Besides performing an important function in the simple act of coupling cars together, the spring in the coupler head has to perform another part with which it is probably not generally credited. It requires about 1 ton pressure to couple two large draw-bars. This helps to cushion the shock at the instant of coupling.
The company with which the writer is connected has lately brought out a very heavy type of coupler, and in this heavy type has embodied some new features, including large round pins. This assures great durability as well as strength, and longer life of pins and links. The round pin draw-bar, No. 19, illustrated in Fig. 4, is of this design. It is sufficiently heavy for such use as would be given in any steam railroad service or on an electrically-equipped steam road.
It takes more than a pair of coupler heads and a coupling device to successfully operate cars and trains. The draft rigging under the car is no less important. In this connection it may be interesting to look at some of the common forms of draft rigging used on elevated and interurban roads. Fig. 4 shows a general form of draft rigging which is quite commonly used. The stem of the draw-bar goes through a stop casting, on either side of which are the buffing springs. The stop casting is riveted to a solid steel plate 8 ins. wide and 1 1/2 ins. thick. This plate runs back to the king bolt of the truck on which it swivels, or to any other swivel that may be provided. A modification of this plan is shown in Fig. 5, where nothing but a short swivel can be used because of the arrangement of car and platform sills. Fig. 6 is another way of securing a long swivel, and can be used where plenty of room is available.
In conclusion, it can be said that the production of a successful automatic coupler for electric roads is much more difficult than the production of an automatic coupler for steam roads, because of the necessary introduction of the swiveling feature on any electric railway draw-bar and the frequent pushing strains with the multiple-unit system. At the same time good automatic couplers are even more necessary on electric than on steam roads, because of the dangers in coupling on electric railways with makeshift types of non-automatic draw-bars, as the radius bar in such times is liable to shift in position or buckle out, and this makes it more dangerous than it was formerly on steam roads with a hand couple. Many people have been under the impression that the M. C.B. type could be used to work on a radial bar. I have had plenty of experience with this, and have found it is absolutely impossible to make a successful draw-bar on these lines. There is trouble making a tight lock, and further, for interurban service, the cars overhang so far from the trucks that unless the tracks are free from sudden changes of grade and almost perfect, the draw-bars oscillate up and down, and one will go right over the top of the other. The coupling must be such that they are held rigidly together, so that no difference what the unevenness of the track may be, they cannot separate. If the lock is not absolutely tight, the bars will swing sideways and buckle on the push.
For more information on how your railway can benefit from the use of Van Dorn Automatic Couplers, Van Dorn MCB Couplers or even Van Dorn Target Ends, click here.
No comments:
Post a Comment