March 1, 1917.] 



THE INDIA RUBBER WORLD 



329 



New Machines and Appliances. 



M 



•J; 



AUTOMATIC STRENGTH AND ELASTICITY TESTEE, 



THIS instrument is constructed so that it generates its own 

 power by the use of a weighted carriage, the speed being con- 

 trolled by an oil filled cylinder. Thus the material to be tested 

 is stretched in a uniform manner dur- 

 ^^" ing the testing period. It is used for 



testing yarns, threads and both vul- 

 canized and unvulcanized rubber. 



This instrument is made for break- 

 ing strengths of from S to 3.0OU 

 grams or 1-5 of an ounce to 6yi 

 pounds. 



To improve the sensitiveness ot 

 this instrument its strength scale is 

 made in two parts, one for the fine 

 yarns having a breaking strength of 

 only a few ounces, and the other for 

 the coarser ones. For the latter an 

 additional weight is added to the u])- 

 per weight lever. 



In this apparatus the piston rod is 

 connected with a carriage which holds 

 the lower set screw. To prevent vi- 

 brations this carriage glides on roll- 

 ers along the standard and a special 

 guide bar. This carriage is held in 

 its upper position by a lever and it is 

 in this position that the oil has to be 

 poured into the cylinder, when setting 

 up the instrument. The tests may be 

 made in two ways, viz : 



By either fixing a single length oi 

 thread, or threads, between the upper 

 and lower screws, or by placing the 

 threads upon a little wheel placed on same pin as the upper 

 screw and tightening the two ends with the lower clamp screw. 

 In the latter case a double length is tested and accordingly'- 

 the strength result has to be divided in two, since two lengths 

 are tested at one time. 



The elasticity in both cases is shown for the single span and 

 this is either in millimeters or inches and fractions and also 

 in per cent directly. 



The strength dials are made either in English or metric system 

 of weight. [Alfred Suter, New York City.] 



A LARGE MAGNETIC CLUTCH INSTALLATION. 



That all rubber mills should be provided with a positive, quick- 

 acting clutch on the mill lines is without question. The danger 

 of operatives being caught in the rolls is ever present, and in 

 case of accident serious injury may be mitigated and the loss 

 of life prevented by an efficient clutch installation. It is, more- 

 over, an important power economy in that it gives gradual ac- 

 celeration in starting the heavy mill rolls. 



The illustration shows a 78-inch C. & H. magnetic clutch, with 

 a capacity of 2,200 horse power at 100 revolutions per minute, 

 that was recently installed in the plant of the Goodyear Tire & 

 Rubber Co., Akron, Ohio. It is said to be the largest clutch of 

 this type in the rubber mill service. The clutch consists of a 

 solid circular steel casting mounted on the mill end of the shaft, 

 having embedded in its periphery a single cylindrical magnetizing 

 coil, the terminals of which are brought out to an ordinary pair 

 of slip rings. Mounted concentrically with the coil and outer 

 periphery is an adjustable friction ring so that the metal faces 

 of the driving and driven member do not come directly in con- 



tact with each other. This also serves the purpose of a perma- 

 nent air-gap in the magnetic circuit. The other member of the 

 clutch, keyed to the driven or rope-pulley side of the shaft 

 through a flexible coupling, consists of a circular steel armature 

 secured to the hub by a fiat circular spring plate. When the mag- 



netizing coil is energized, this, circular armature is drawn towards 

 the driving metnber of the clutch, the motion along the shaft 

 being accompUshed by a sligh't dishing of the spring plate upon 

 which it is mounted. This particular form of clutch possesses 

 the advantage of instant disconnection in case of interruption of 

 the magnetizing current, and does not require a portion of a 

 revolution for its disengagement. There is no tendency, more- 

 over, for it to either release or to lock itself due to the mechan- 

 ical forces exerted as it cOmes up to speed and while it is run- 

 ning at full speed. 



There is a slack cable switch mounted in a frame on the 

 right of' the clutch connected to a rope and overhead torsion 

 rod, which automatically causes the clutch to disengage in case 

 any of "the driving ropes of the main steam engine drive should 

 break. [The 'Cutler-Hammer Clutch Co., Milwaukee, Wisconsin.] 



THE GRUNDY FLEXIBLE INSULATED COUPLING. 



W'here it is difficult to get the shaft bearings in perfect aline- 

 ment, or where they are liable to get out of line, the simple 

 and effective device here shown is recommended for connecting 

 the two ends of the shafting. It is constructed of three pieces, 



the two outer flanges being of cast iron and the center disk 

 of leather or hard fiber with lugs on each side for transmitting 

 the power to the outside flanges. 



The leather lugs are cut on a bias, tapering towards the disk, 

 the cast iron driving flanges being machined with a correspond- 

 ing taper, which has a tendency to draw the flanges close to 

 the disk, and to cause the leatlier lugs to receive and transmit 

 the power at their strongest points. 



The close connection made possible by this type of coupling, 



