Spud Leads

1. It requires only a two-hoist drum crane. 2. It provides accuracy in locating leads in all batter positions. 3. It provides rigid control of the leads during positioning operation. 4. It allows batter angles to be set and accurately maintained. 5. It allows for the use of short boom angles that increases the crane capacity. 6. The boom can be lowered and leads folded under for short hauls over the road when a crane with adequate capacity is used This operation depends on the length of the lead and boom and the configuration of the crane. DISADVANTAGES.— Some disadvantages of using an extended four-way lead are as follows: 1. It is the heaviest and most expensive of the three basic lead types. 2. It is more troublesome to assemble. Spud Leads A spud lead is a steel wide flange or H-beam used in place of pile-driving hammer leads. The pile-driving hammer rides on the flange of the beam through spud clips bolted to one side of the pile-driving hammer (fig. 12-58). Depending on the design of the spud lead, the spud can be used as a swinging and underhung lead or equipped with a sheave head assembly as an extended four-way lead An advantage of this type of lead is that it bears the whole bottom of the pile cap to the piling especially when sheetpiling is being driven (fig. 12-59). PILE-DRIVING HAMMERS The three principal types of pile-driving hammers are the drop hammer, the steam, or pneumatic, hammer, and the diesel hammer. A drop hammer is a block of metal hoisted to a specific height and then dropped on a cap paced on the butt or head of the pile. Drop hammers weigh from 1,200 to 3,000 pounds. WARNING The noise generated by a pile driving operation can cause hearing loss. Hearing protection must be worn by personnel in the vicinity of pile driving operations. Figure 12-58.-Spud clips mounted to one side of the pile- driving hammer. Figure 12-59.-Sheet pile driving with spud leads. 12-41