Fasteners and Connections

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Figure 21. Float Pin

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Weight Handling Equipment

Built-Up Hoists

MIL-HDBK-1038

The newer cranes have identical (or mirror image) powered trucks with one

driven and one idler wheel. All gearing is enclosed (inside gear reducers) with

the output shaft connected directly to the wheel axle. Except for the wheel

pockets at the ends, these travel trucks are sealed box weldments.

4.2.11

Fasteners and Connections. Keeper bars on various components pivot

pins, rocker pins, boom hinge pins, roller path fixed axles not being subjected

to any calculable or significant loads, are secured with two screws torqued to the

mechanical design criteria. Screws and bolts holding caps and

retainers over bearings and bushings in most cases are likewise out of any direct

load path, and are torqued to the mechanical design criteria. Fastener sizes are

selected to nominally match the dimensions of the surrounding structure and the

installation torque is often governed by the strength of the tapped threads in the

base material. (Fasteners which are in direct load path must be individually

analyzed and sized according to the applicable design criteria.) All these

fasteners, are required to be locked against loosening, either by means of lock

washers or lock wiring of their heads to each other or the adjacent structure.

Bolts and studs holding the roller path rail segments are required to

comply with the structural design criteria. When the rail segments are embedded

in an epoxy resin compound, their installation must follow the recommendations of

the resin manufacturer. The bolts or studs securing the rotate bearing to the

crane structure must be selected and installed according to the bearing

manufacturer's requirements.

Bushings and thrust washers that have grease grooves that require

alignment with grease injection holes must be fastened to their support structures

with threaded fasteners. Flangeless bushings may be locked in their housings with

setscrews installed in tapped pockets at the press fit bore. Flanged bushings and

thrust washers may be secured with counterbored or countersunk screws. These

fasteners should be locked against backing out by staking.

4.2.12

Wire Rope Pendants. Stationary wire rope assemblies, such as pendants,

should use 6x37 or 6x19 classification bright or galvanized wire rope with poured

(zinc or resin) sockets or swaged fittings.

4.2.13

Painting and Corrosion Protection. Structural-mechanical components

should be painted for corrosion protection in the same manner as the structural

components and weldments, described in paragraph 4.1.29 and subparagraphs but

with the following exception:

Working surfaces those subjected to rolling, sliding, or pivoting

motion must be left unpainted. (The relative motion with mating surfaces, and

periodically applied lubrication, prevent corrosion on them. Various pins, roller

treads, rail and roller path running surfaces are in this category.)

Corrosion resistant metals and plating should be left unpainted.

(Stainless steel, copper alloys, aluminum, galvanized wire rope pendants, and

chrome plated steel pins are in this category.)

Lubrication fittings must be left unpainted.