to the hammer line, has jaws on the side to engage the guides, and rests on and is free to follow the pile. The striker (or striking parts) consists of a steam cylinder and piston. The striking weight may be attached to either the piston or cylinder, dependent upon which is the moving part.

FIG. 21.-Warrington steam hammer, single acting. Vulcan Iron Works, Chicago, Ill.

Steam hammers may be either single acting (Fig 21)-as when steam is employed simply to raise the striking weight, which then falls by gravity-or double acting (Figs. 22, 23, and 24), when steam not only raises the weight but is also employed to aid the action of gravity in striking the blow. The total weight of a steam

hammer is much greater than the weight causing the blow, but, as the frame rests on the pile, this weight tends to keep the pile in motion after it is started and eliminates vibration to a large degree. The length of stroke being short, about 24 to 42-in. blows are delivered in rapid succession, so that the pile is in more nearly continuous motion than it is when drop hammers are used. In general, the double acting hammer is lighter, its length of stroke is shorter, the weight of striking parts is less, and the number of blows per minute is greater than in the single acting hammer, but in beavy driving the single acting hammer with heavier ram finds preference.

Numerous advantages are claimed for the steam hammer. Among these are: (1) serious damage to the pile, such as brooming, splitting, etc., is avoided, therefore saving the expense of putting rings on the head of the pile and also allowing the use of softer woods; (2) more

piles may be driven in a given time with a smaller crew; (3) less injury is caused to adjacent buildings by cracking of plaster, breaking of glass, etc; (4) the life of the leads is increased 3 to 4 times; (5) the cost of driving is less in spite of higher first cost; and (6) ease of driving is greater, as the pile is kept in motion so that ground resistance is reduced.

Special hammers of lighter weight and having a special cap are used to drive sheet piling.

7c. Pile Caps, Points, and Pullers.-With timber or concrete piles, a driving cap is used between hammer and pile head. This cap (Fig. 25) consists of a metal block, one side of which is concave, the other recessed, in which is fitted a round wood cushion block. In cross section it resembles a drop hammer having jaws in the sides to engage the guides and is attached to the hammer by rope slings. When a cap is used, the hammer base is flat, but with timber piles, if no cap is used, the base is concaved to fit the head of the pile. If the use of such a cap is insufficient to prevent brooming or splitting of the head of a pile, an iron ring, made from flat wrought iron from 2 X 3% in. to 4 X 1 in. may be forced over it. Such rings may be removed and used over again many times.

Dia 2 Dia.,
Top Plate
Dia
Bottom Plate

Cap Block

Cable clip side of sling on front side of driver

14 Dia Method of driving

out used up block

(a)

(e)

FIG. 25.-Raymond pile cap.

(c)

FIG. 26.-Steel sheet piling caps of the Lackawanna
Steel Co.

Pile Points or Shoes.-Timber piles drive better in ordinary ground and with less danger of splitting if the tip is square, and without point or shoe. This also gives a better footing to the pile. When coarse gravel, boulders, and the like are encountered, the pile is preferably pointed to reduce splitting and crushing. Likewise, in hard compact earth which must be displaced, pointing is found to give better results.

Metal shoes are provided in some cases when boulders, riprap, very hard clay, and hardpan are encountered. Several types are in use, but the type which gives a square bearing to the tip of the pile, and also sufficient socket to make the pile and the shoe act together, is the most desirable. Some shoes for wood piles are made with a rod which fits into the center of the pile as an additional means of holding pile and shoe together. This rod is from 8 to 12 in. long and requires that provision be made for it in the pile. Precast concrete piles, if of good quality, should not require driving shoes.

For Sheet Piling.-Caps and shoes are not generally required for timber sheet piling as, due to their section, such protection is not necessary. In some cases, a bolt or short point is at

tached but as a means of keeping the groove clean throughout its length so that grouting may be employed to insure a tight waterproof joint rather than as a penetrating point.

With steel sheet piling, caps are used when necessary to fit the piling shapes to the various types of hammers. Such caps are attached to the hammer with rope slings; and where guides are used, the cap is equipped with jaws. The caps serve not only to distribute the blow and to lessen possible injury to the top of the pile but also to keep the piling in position (Figs. 26, 27, and 28).

Pulling.-Piles and sheet piling, particularly steel sheet piling, are preferably removed when that part of the work for which they were used has been completed. Piling may be removed by jacks, or by inverting the hammer if a steam or air hammer is used, or by levers.

In the case of round piles, a sling is put around the head and attached to a long lever, this lever being operated by derrick, jacks, or some other convenient means with new hitches taken as the piling moves. Often it is necessary to strike a few blows with the hammer to start a pile, or else to keep the sling taut for some time before the pile begins to move. Concrete piles are not used for temporary construction work and rarely have to be removed, though the same general procedure outlined above would be applicable to them.

Pulling of sheet piling is done either with levers, hydraulic jacks, or by inverting a steam hammer (Fig. 29). With either of these appliances a yoke of steel plates having holes drilled in it to correspond with holes in the piling, is fastened to the latter by bolts (Fig. 30). The upper end of the yoke is attached to the lever or hammer and power applied. Patented pullers are also used. Several are shown herewith whose aperations may be readily understood. The principle of these pullers is that the greater the effort exerted, the greater the grip and the quicker and easier the release after pulling.

PUMPING EQUIPMENT

BY NATHAN C. JOHNSON

Water in excavations or in footings or trenches must be removed by pumping. The size and type of pump to be provided for this purpose will depend on the amount of water accumulated or flowing in, the depth of cut, and the character of power available. As clearing away such water is, in most instances, a necessity, the cost of the operation is a secondary consideration.

8. Hand Lift Pumps.-For small amounts of water and low lifts, the direct lift hand pump may be employed. As this pump is made of either a sheet-iron tube or square wooden box having an ordinary flap valve at its lower end with a piston carrying another flap valve worked up and down in the tube, it may be constructed on the job, but it is slow in operation and easily clogged by refuse.

9. Diaphragm Pumps.-A better type of pump even for small quantities of water with low lifts is the diaphragm pump. It consists of a rubber diaphragm containing a flap valve mounted horizontally in a cast-iron cylindrical frame. Connected with the center of the diaphragm is a pivoted arm which, when moved, causes the diaphragm to act as a piston of large area and short stroke. A suction line, usually of rubber hose of large diameter, connects with the space, or cylinder, beneath the diaphragm piston. These pumps are preferably actuated by a gasoline engine, but hand or motor drive may be had. This type of pump will not become clogged easily and will pass straw, leaves, etc., and may be obtained mounted on a small truck, so as to be portable.

Hand operated diaphragm pumps have a capacity of 30 to 100 gal. per min. A pump of 60 gal. per minute capacity, weighing 75 lb., will cost about $35 not including strainer, foot valve, and hose. These are extras with all pumps.

Gasoline driven diaphragm pumps range in capacity from 30 to 300 gal. per min. Such a pump mounted on iron skids and having 150 gal. per min. capacity for lifts up to 20 ft., will weight 625 lb. and cost about $325. Truck mounting will increase the weight slightly and the cost about $25.