SPECIFICATIONS FOR STEEL MINE STRUCTURES. 



225. Coal Tipples or Dumps. Coal tipples or dumps shall be provided as shown on the detail 

 plans or called for in tin- specifications. 



226. Dumping Devices. Where self-dumping skips or cages are used an efficient and satis- 

 l\n lory (lumping device shall be provided. 



227. Head Sheaves. The head sheaves shall be substantial with the top flanges turned 

 smooth and true to receive the hoisting rope. The sheave wheel shaft shall be of the best grade 

 of machinery steel of ample strength, carefully and truly made. The sheave boxes shall be lined 

 with the l>est quality of anti-friction metal and shall be adjustable to take up the wear. Unless 

 otherwise specified the sheave wheels shall have wrought iron spokes. 



228. Landing Stage. An efficient landing device shall be furnished. 



DETAILS OF CONSTRUCTION. 



229. Unless otherwise provided for the details of construction are to be the same as for 

 steel frame buildings. 



230. Design. In designing head frames, coal tipples, coal washers and breakers and similar 

 structures care shall be used to strongly brace the different parts of the structure in order that it 

 may be rigid. Preference shall be given to types of structures that are statically determinate. 

 Where 4-post head frames and other statically indeterminate structures are used the stresses shall 

 be calculated by taking account of the deformation and distortions of the members.* All bracing 

 is to be made of stiff members; the use of rods or bars will not be permitted, except for sag rods 

 and anchors. It is very important that head frames, coal tipples, coal washers and breakers and 

 similar structures be made very rigid. 



231. Lengths of Compression Members. The length of compression members in head 

 frames and shaker structures shall not exceed 100 times the least radius of gyration for main 

 members nor 140 times the least radius of gyration for secondary bracing. 



232. Lengths of Tension Members. The length of tension members in head frames shall 

 not exceed 150 times the least radius of gyration for main members, nor 200 times the least radius 

 of gyration for secondary bracing. The length of a tension member is to be taken as the distance 

 center to center of end connections. 



233. Splices. All splices in main members shall be designed to carry the full strength of 

 the member. 



234. Reaming. The rivet holes for all field splices shall be punched to a diameter ^ in. less 

 than the finished hole and shall be reamed to the required size with the members bolted in place 

 with an iron templet. All metal more than f in. thick shall be punched and reamed, or be drilled 

 from the solid. 



235. Minimum Thickness of Metal. The minimum thickness of metal in plates and sections 

 shall be fg in., except for fillers. 



236. Erection. All field connections shall be riveted. Before the riveting is begun all field 

 connections shall be fully drawn up with field bolts, in not less than one-half the holes of each 

 joint. 



237. Materials and Workmanship. All materials and workmanship shall comply with the 

 Specifications for Steel Frame Buildings unless otherwise specified. 



238. Painting. All steel work shall receive one coat of satisfactory graphite or carbon paint 

 at the shop. Before erecting all abraded spots shall be touched up, and all rivet heads shall be 

 painted as soon as accepted by the inspector. After the erection is complete all structural steel 

 work shall be given two coats of satisfactory graphite or carbon paint. The three coats of paint 

 shall be of different colors. 



REFERENCES. For additional data for the design of head frames, rock houses, coal tipples 

 and other mine structures, and for numerous examples of structures, see the author's ' The 

 Design of Mine Structures." This book gives the calculation of stresses in head frames, and also 

 gives a full discussion of the details of design of mine structures, including specifications, methods 

 of construction and costs. 



* For the calculation of the stresses in mine structures, see the author's "The Design of Mine 

 Structures." 



