fore vitally interested in the tower design in all details. cal problems consisted of designing the following. The mechani- Design work on the mechanical portion of the 300 foot towers was started by the middle of October 1948. This consisted of preparation of drawings M-l through M-5. At the beginning, this work was guided by "Preliminary Specification 250'-300' Steel Tower," Consolidated Steel Corporation shop drawings for 200 foot steel towers previously used by AEC for Operation Sandstone, and verbal instructions and information - all of which were furnished by a representative of Sandia Corporation. This information provided the Mechanical Department with valuable criteria gained from experience, Because mechanical design was closely coordinated with structural design as each progressed, the necessity for changes was minimized, The mechanical design problems consisted of: 1. A main hoist capable of handling 10,000 pounds on a 2-part line with a maximum hoisting speed of 30 fpm, from ground level to the tower cab, 2. A skip hoist (elevator) for personnel and freight, capable of handling a net load of 2,000 pounds on a 2-part line with a maxi- mm hoisting speed of 125 fpm from ground level to the tower cab. Hoisting speed was established by Sandia Corporation on October 27, 1948. 3, A hand winch and accessories located in the tower cab for pulling coaxial cables up on messenger cables, This was requested by Sandia Corporation on November 3, 1948. The main hoist consisted of a 900 pound load block on a nonrotating steel cable, The sable was reeved over a series of steel sheaves which were mounted on the structural A-frame at the top of the tower, above the tower cab, From these sheaves the cable ran down outside the tower to the main hoisting machine which was located on the ground outside of the tower, One of the criteria for the tower vator that could be operated from the the skip itself should be installed. with safety devices for protection in was that a personnel skip or eleground, from the tower cab, or from This skip was to be fully equipped case of accident to the hoist cable or to the hoisting equipment itself. Although such safety devices were in common use in modern commercial buildings, these devices did not fit the requirements of the tower. Ordinarily, elevators are lifted from above, but the tower skip was to be lifted from below the skip platform. Comercial safety devices were much too complicated for use on the skip, 30 an entirely new system of safety mechanism was developed by Holmes & Narver and tested to the satisfaction of all concerned. The skip hoist consisted of an open type platform (elevator cab), traveling on elevator-type steel guide rails which were attached to the tower, The platform was raised and lowered by a steel cable which was reeved over a series of steel sheaves mounted below the house floor at 5-131