COUPLERS, CAR-. The requirements of an efficient car-coupler are thus summed up by Prof. S. W. Robinson : 1. That they be coupled and uncoupled without requiring men to go between cars. 2. That, whatever the relative heights of the couplers, they couple and uncouple equally well. :3. That free slack, as far as possible, be dispensed with, to reduce damage to equipment and freight. 4. That cars can be coupled easily and with a minimnin of concussion, to encourage careful handling of cars. 5. That they be simple and durable, and at a minimum of cost. 6. That the couplings at both ends of a car tie alike. 7. That there be no loose parts to be lost. 8. That they couple on curves. P. That they couple with certainty, and remain so without danger of parting on the road. 10. That they he such as act favorably with brakes. 11. That coupling and uncoupling be unobstructed by inclement weather. 12. That the coupling be universal, or readily connecting with all oilier couplers. 13. That they do not occupy excessive room in a train, to give it Ilmthe length.
As the result of protracted experiments, Prof. Robinson concludes: 1. That the avoidance of 4- free slack" is one of the most important steps to be taken in the freight-ear coupler, and that this is only second in importance to the adoption of such devices as shall be automatic, and not hazardous to the lives of trainmen in operating. 2. That the threefold numerous dimensions to be provided for in the link and pin coupler, as compared with hook-couplers, and with the link and pin, the free slack is greater than in hook-couplers. to dis astrous conswpa'nces. while hooks it can he reduced to practically nothing. 3. That with hook-couplers the rigging at both ends of a car can be positively identical, with no detaehable parts, whereas with the link and pin this is impossible. 4, That close hook (ampler, can be much lighter than in those where severe vonenssions occur. iv in the link and pin. 5. That close hook-couplers serve much more favorably than others in connection with all kinds of brakes. Pigs. I to 19 represent the principal forms of car-couplers in use in the Cnited States, ana the following table gives particulars concerning them : Standard Coupler-Gang e.—This has been adopted by the Executive Committee of the Master Car-Builders' Association, for the purpose of determining whether couplers are near enough to the standard contour established by the Association to insure proper coupling with one, another, in so far as it enn he insured by close adherence to the standard contour, and also In establish limits of variation for such of the standard rectilinear measurements of the coupler, only, as will promote the interchangeability of couplers ia place upon cars.
The gauge for new couplers, shown in Fig. 20, provides means for gauging the contour lines, the thickness of the knuckle, at points throughout the whole essential extent of the standard form of contour, and it controls the variation in both directions from the standard.
The gauge for new knuckles, shown in Fig. 21, allows in. variation each way from the standard dimensions of 3 in. Fig. 22 shows the lim its of standard rectilinear measurements, The limits shown in the table are proper limits of variation for the standard rectilinear measurements.
Recent Improvements hi lers are almost invariably automatic. The standard contour is closely followed. Among the more impor tant recent improvements is a change in the location of the link-pin hole on the end of the knuckle, made by moving it toward the interior face about in. This gives a large increase in the thickness of metal between the link-pin and the outside face of the knuckle, and tends to reduce breakage. Another improvement is a movement of the pivot - pin away from the end of the coupler to a sufficient extent to allow a portion of the knuckle to pass outside the pivot-pin lugs. This has two beneficial effects; it strength ens the knuckle considerably, and serves as a protection to the lug. There is an increase in confidence in the use of east, steel for couplers. Knuckles are of three kinds—east steel, forged steel, and wrought iron. Self-opening knuckles and those that may be opened from the side of the ear are prominent. Devices have been introduced for overcoming the necessary differences in the lateral displacement of the ends of cars of different lengths on curves. These are of two sorts : one, for the back of tenders, has the form of a pivoted coupler-head ; another, for freight-cars, has a spring on either side of the drawbar, which permits considera ble lateral motion, and yet returns the coupler to the center on a straight track.
(See files of the Railroad Gazette and Proceedings of Master Association.) Couplings: see Carriages and Wagons, Clutches and Couplings, and Fire Appliances. Covering Boiler : see Boilers, Steam.