OO-C-2764 Cranes, Crawler Mounted, Commercial, Ded

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OO-C-2764

specified in 4.4.9. The clutches shall be unlocked by pulling or pushing

forward on the control lever. Clutches shall be controlled by mechanical

linkage, air, manual effort applied through hydraulic linkage, or by full power

hydraulics.

3.11.5.4 Auxiliary drum. When specified (see 6.2), an auxiliary drum, used

for pile-driving operation, shall be provided for the crane. The drum shall be

engaged by a clutch operable from a control lever in a position within-easy

reach of the operator while seated.

3.11.6 Rollers.

3.11.6.1 Supporting rollers. The rotating frame shall be supported by large

fixed rollers or by a live ball or roller ring. The rollers shall be

heat-treated steel and shall be accurately machined. Fixed rollers shall be

fitted with antifriction or bronze bearings, with grease fittings. When the

revolving superstructure is tested in accordance with 4.4.7, the temperature

rise of the supporting balls or rollers shall be not more than 175 deg F. The

balls or rollers shall be accessible and shall be removable.

3.11.6.2 Hook rollers. Where the holddown function is performed by hook

rollers, the rollers may be of the dual-purpose type in which one set of rollers

performs both the supporting and holddown functions of they may be of . the

holddown type only. Hook rollers may operate singularly or in pairs of tandem

bogies and shall be provided with grease fittings. Hook rollers shall be

provided with means for vertical or horizontal adjustment.

3.11.7 Swing. When the revolving superstructure is tested in accordance

with 4.4.8, the swing speed shall be not less than 2 rpm for size 1, 2 rpm for

size 2, and 2 rpm for the remaining sizes.

3.11.7.1 Swing mechanism. The swing gear pinion shall have accurately

machined or ground teeth of alloy steel. The swing gear pinion shall operate in

antifriction or bronze bearings equipped with means for lubrication. The

rotation of the rotating frame shall be controlled by a hydrostatic drive system

or through friction or electromagnetic type clutches designed for fast cycling,

craning, and other operations, and with a clutch capable of transmitting not

less than 75 percent of the maximum engine torque. The temperature of the swing

clutches shall not exceed the maximum temperature recommended by the clutch

lining manufacturer. Clutches shall be of the friction or electromagnetic type,

and shall be controlled by mechanical linkage, air, or manual effort applied

through hydraulic linkage, or by full power hydraulics.

3.11.7.2 Swing lock or brake. A swing brake, controlled from a position

within easy reach of the operator while seated, shall be provided to hold the

superstructure in any desired position. When specified (see 6.2), a separate

superstructure lock shall be furnished to prevent the swing of the revolving

superstructure.

3.11.8 Power transmission. Unless otherwise specified (see 6.2), the engine

shall be connected to the transmission through either friction clutch or

friction disengaging clutch and fluid coupling. When specified (see 6.2),

friction disengaging clutch and a hydraulic torque converter of commercial

standard design, which has been proven satisfactory in extensive crane use,