Very often the cycle of operation of a hoist is of an intermittent character. The power required is at a

Table XX. Tables Of Sizes Of The Lambert Hoisting Engines

Horse-Power Usually Rated

Dimensions of Cylinders

Dimensions of Drums

Weight

Hoisted,

Single Line

Suitable

Weight for

Pile Driving

Hammer for

Quick Work

Diameter (Inches)

Stroke (Inches)

Diameter (Inches)

Length between

Flanges (Inches)

10

5 1/2

8

12

16

2,500

1,600

14

6 1/2

8

12

16

3,000

2,000

20

7

10

14

18

5,000

3,000

25

7 1/2

10

14

24

6,500

4,000

30

8 1/2

10

14

24

8,000

5,000

35

9

10

14

24

9,000

5,000

40

9 1/2

10

16

23

10,000

6,000

maximum only a part of the time, even though the hoist may be operated practically continuously. From an economical point of view, these conditions give the electric motor-driven hoist special advantages, in that the electric hoist should always be ready, but using power only when in actual operation and then only in proportion to the load handled. The ease with which a motor is moved, and the simplicity of the connection to the service supply, requiring only two wires to be connected, are also in favor of the electric motor.

Fig. 136 shows a motor made by the Westinghouse Electric & Manufacturing Company, which is designed for the operation of cranes, hoists, or for intermittent service in which heavy starting torques and a wide speed variation are required. The frames are enclosed to guard against dirt and moisture, but are so designed that the working parts may be exposed for inspection or adjustment without dismantling. These motors are series-wound, and are designed for operating on direct-current circuits. The motor frames are of cast steel, nearly square in section and very compact. The frame is built in two parts, and so divided that the upper half of the field can be removed without disturbing the gear or shaft, making it easy to take out a pole-piece and field-coils, or to remove the armature. Fig. 137 shows the controller for this type of motor. These controllers, when used for crane service, may be placed directly in the crane cage and operated by hand, or mounted on the resistance frames outside the cage, and operated by bell cranks and levers, so that the

FRONT AND REAR VIEWS OF RESIDENCE FOR MR.PERCY B.ECKHART, KENILWORTH, ILL.

FRONT AND REAR VIEWS OF RESIDENCE FOR MR.PERCY B.ECKHART, KENILWORTH, ILL.

W. Carbys Zimmerman, Architect, Chicago, 111.

Built in 1906. Cost, $10,000. Stud Walls with Plaster on Wire Lath. First and Second Story

Plans Shown on Opposite Page.

FIRST  AND SECOND STORY PLANS OF RESIDENCE FOR MR. PERCY B. ECKHART,

FIRST- AND SECOND-STORY PLANS OF RESIDENCE FOR MR. PERCY B. ECKHART,.

KENILWORTH, ILL.

W. Carbys Zimmerman, Architect, Chicago, 111.

Exteriors Shown on Opposite Page.

Masonry and reinforced concrete 283 attendant may stand closer to the operating handles and away from the contacts and resistance.

Polyphase induction motors are being used to some extent for general hoisting and derrick work. These motors may be of the two-phase or three-phase type; but the latter are slightly more efficient. These motors are provided with resistances in the rotor circuit, and with external contacts tor varying the same. Two capacities of resistance can be furnished: (a) Intermittent service, zero to full load; and (b) Intermittent service, zero to half-speed; and continuous service, half-speed to full speed. The controllers are of the drum type, similar to those used on streetcars.

Fig. 135. Ransome Friction Crab Hoist.

Fig. 135. Ransome Friction Crab Hoist.

Fig. 136. Motor with Fields Parted. For operation of cranes, hoists, etc.

Fig. 136. Motor with Fields Parted. For operation of cranes, hoists, etc.