Question_15 Revised Spec.pdf

the motor frame or in the motor lead terminal box as selected by the motor manufacturer.

2.6.4 Motor Encoders

a. Hoist Motor Encoders: Provide Heavy Duty quadrature phasing magnetoresistive or optical encoder compatible with motor and drive that provides an A and B pulse signal corresponding to speed and direction. The encoders must be supplied and factory installed by the same manufacturer as the hoist motors. Environmental ratings are to be NEMA 3R or IP56 equivalent. All encoders are to be protected by a metal cage from damage.

2.7 HOLDING BRAKES

2.7.1 Brake Type

a. Provide submittal for the Holding brakes. Each hoist motor, except the clamshell closing hoist, auxiliary hoist, and tool hoist, must be provided with two holding brakes as shown. The clamshell holding hoist shall have two holding brakes. Each travel motor is to be provided with one holding brake, mounted on the motor shaft. Brake ratings, dimensions, and performances must conform to NEMA ICS 8 and AISE Technical Report No. 11, except as otherwise specified. Brakes must be identified by the manufacturer as being "AISE-NEMA" compliant.

(1) Main Hoist and Clamshell Holding Hoist brakes shall be similar type of one of the following:

(a). Mill duty, shoe type, spring set, rectifier-operated, with armature-actuated, direct-current, shunt-wound coil magnet release, Class F or H insulation, having additional manual release mechanism that is self-resetting.

(b). Mill duty, shoe type, spring set, AC operated, having additional manual release mechanism that is self-resetting, equal to Mondel Type MBT as manufactured by Mondel Engineering.

(2) Aux. Hoist, Gantry Travel and Trolley Travel. As required above, or mill duty, motor-mounted flat-plate friction type, spring set, rectifier- operated, with armature-actuated direct-current, shunt-wound coil magnet release, Class F or H insulation, having additional manual release mechanism that is self-resetting. Solenoid-actuated brakes will not be accepted.

b. Shoe brakes must be completely enclosed as directed in Paragraph "Brake Enclosing Case." All disc brakes must have NEMA Type 4X (IP56) or better enclosure rating. Nameplates must be provided for each brake and attached to a part of the brake which ordinarily will not be renewed during its service life. Each nameplate must conform to Part 10, paragraph 5.6 of NEMA ICS 8, clearly indicating the manufacturer's name, identification symbols, serial number, and salient design features such as type, frame, torque rating and voltage.

2.7.2 Brake Release

a. Brake releasing actuating equipment must be suitable for operation on power supplied by the crane. The complete unit (brake and rectifier, as applicable) must be suitable for connection to the control circuit and the AC power circuit of the motor with which the brake is used so that the brake will set and release when the motor is de-energized, and energized, respectively.

b. For dc brakes, direct-current is to be supplied by means of a dedicated rectifier and control unit of proper rating. The rating of the brake releasing magnet must be sufficient to release and hold the brake in the released position with 80 percent or less of rated voltage impressed on the incoming terminals. Brake control unit must be complete with transformer, rectifier, brake contactor, protective fusing, and control board. Brake control unit is to be mounted in the control panel, adjacent to the associated motor controller.

c. The brake control unit must be approved, for use with the brakes, by the brake manufacturer.

2.7.3 Brake Mechanical Construction

Except for brake base, brake wheels, shoes, shoe holders and electrical parts, no cast iron can be used in brake construction. All allowed cast iron components except electrical parts must be ductile iron. All pins, fittings and other miscellaneous small metal parts must be of corrosion-resisting metal or be treated to render corrosion resistant by galvanizing; sherardizing; or plating with zinc, cadmium or copper.

Bearings must be fitted with bronze or other approved bushings to prevent any binding of moving parts. Antifriction bearings of corrosion-resisting construction may be used. Adequate means must be provided for lubricating oil bearings, unless the bearings are of an approved self- or pre-lubricated type. All brake wheels must be mounted so that shaft and keyway extend all the way through the brake wheel. Outer diameter of brake wheels must have runout tolerance of 0.005 inch, and be dynamically balanced such that at operating RPM, they meet balance quality grade of ISO 1940-1 G 2.5.

2.7.4 Brake Torque Rating, Duty, and Adjustment

a. Certification of factory adjusted torque rating of holding brakes are to be submitted for approval. Torque rating of brakes must be referred to the shaft on which the brake wheel is mounted, the efficiency of the speed reducer not being considered. Torque and duty ratings must be selected to meet "AISE-NEMA" requirements. Ratings identified by the manufacturer as being "General Purpose" or "Heavy Duty" are not to be used in lieu of "AISE-NEMA" ratings. Torque and duty ratings must be as follows:

(1) Hoist Brakes. Each brake must be rated not less than 125 percent rated motor torque and the brake holding torque set at 125 percent full load motor torque. Hoist brakes must be continuous (8-hour) duty.

(2) Trolley Travel Brakes. Each brake must be rated not less than 100 percent full-load motor torque. Brakes shall be set to a torque capable of stopping the trolley motion within a distance in feet equal to 10% of the rated load speed in feet per minute when traveling at rated speed with a rated load. Trolley travel brakes must be not less than 1-hour duty.