TURBINES 



243 



the rims, the arrangement of the lugs being so designed that the 

 rear lugs of one bucket come directly in line with the forward lug 

 of the next following bucket. A single bolt, therefore, passes 

 through the rear lugs of one bucket, the rims and the central or 

 forward lug of the next following bucket, thus connecting up .all 

 of the buckets into a con- 

 tinuous chain. Fig. 133 

 shows such a type of wheel. 

 In the chain-type wheel 

 the base line of the buckets 

 or the distance between the 

 supporting bolts is very 

 much greater than it is with 

 double-lug buckets. This 

 type of construction is, 

 therefore, particularly suit- 

 able for all installations 

 where the ratio between the 

 diameter of the jet and the 

 pitch diameter of the wheel 

 is small, that is, where a 

 large diameter of jet is 

 applied to a comparatively 



FIG. 133. Tangential Water Wheel 

 Equipped with Ellipsoidal Inter- 

 locking Chain Type Buckets. (Built 

 by Pelton Water Wheel Company.) 



small diameter of wheel. 

 This is always the case 

 where a very large power output is required, with a turning speed 

 comparatively high, as proportional to the head of water, thus 

 calling for large buckets on a comparatively small wheel. It is also 

 especially suitable for extreme cases of large horse-power and high 

 heads, making the wheel runner of the most stable construction. 

 The buckets are ellipsoidal, which causes the water jet to 

 impinge without shock or disturbance, and it is discharged along 

 natural lines over the entire bucket surface. The central portion 

 of the front entering wedge or lip of the bucket is cut away in the 

 form of a semicircular notch, and this opening allows the solid 

 circular water jet to discharge upon the central dividing wedge 

 of the bucket without being split in a horizontal plane, with the 

 result that all eddy currents are avoided and the full force of the 

 jet is expended for useful work, resulting in the maximum bucket 

 efficiency. 



