Masonry Magazine October 1968 Page. 28
"My new Lull 7C2 high-lift gives me 9 more inches of reach... a real bonus!" Wade Lupe, Wade Lupe Construction Co., Inc.
"I bought my first Lull High Lift because I liked the extreme forward reach and the straight and level Para-Plane action. Now my new 40 foot Lull 7C2 gives me 9 more inches of reach! I consider this a real bonus feature in construction work!"
Check these other features:
* Reversomatic transmission with Torque Converter drive. No clutch. Single lever gives you 6 speeds forward and reverse.
* 55 inch transverse action gives you 9 more inches of "reach."
* Most rugged machine of its class on the market. Strongest lift arms ever made. Larger axles for extra strength.
* Full time power steering.
* Independent disc-type wheel brakes.
* Lull designed double acting LIFETIME cylinders. Power up... and down!
* 232 cubic inch displacement engine. 16 cubic inches more than before . . . extra horsepower for tougher jobs!
* Four job-rated models to choose from . . . elevate payloads up to 40 feet!
See your Lull dealer or write today for details. LULL ENGINEERING COMPANY, INC. Dept. M 3045 Highway 13, St. Paul, Minnesoto 55111 for over 30 years
Books... Causes, Mechanism, And Control Of Cracking In Concrete (A symposium volume by American Concrete Institute Committee 224)
Virtually all aspects of the subject on the causes, mechanism, and control of cracking in concrete are covered. Of the 12 papers included in the American Concrete Institute's Special Publication No. 20, the first six deal with the causes and mechanisms of cracking, and the remainder with the prevention and control of cracking. A number of the papers present the results of particular investigations in depth rather than covering a comprehensive history of the assigned portion of the field.
Contrasts are presented to show that in some plain concrete structures, cracking is to be avoided altogether. Here elaborate precautions are taken in mass concrete structures to insure that during the early life of the structure, thermal stresses remain less than the tensile strength of the concrete.
The trend to the use of high-strength steel magnifies the problem, but the difference is purely one of degree since cracking is inevitable even when "mild" steel is used. It must come as a surprise to the layman to discover that the goal of a designer, under these circumstances, is to encourage as many cracks as possible. Since the sum of all the crack widths is more or less fixed and determinate, crack width is inversely proportional to the number of cracks which can be encouraged to form.
Wide cracks are of course objectionable for several reasons. In addition to aesthetic reasons, they increase the steel stress, and also permit the entrance of water or aggressive solutions which might corrode the steel.
Between the extremes of the plain concrete structure whose stability depends on the absence of cracks and the reinforced flexural member whose function dictates an abundance of cracks, there is a gamut of unreinforced or lightly reinforced structures with varying probabilities of cracking.
Available in hard cover volumes. 6" x 9". 246 pages. Price per copy $13.00; to ACI members $9.00. Copies may be purchased from the Publications Department, AMERICAN CONCRETE INSTITUTE, Box 4754, Detroit, Michigan 48219.
masonry • October, 1968