Abstract: The invention relates to a method of dismounting or mounting jib sections on a tower crane, at which a carrying cradle with counterweight and having the form of a three-armed lever is used for lowering or hoisting jib sections to be dismounted and mounted, respectively, and the cradle is so designed as to during the lowering and hoisting operations, respectively, to assume suitable balanced positions.

Abstract: In building a crane, the electrically actuated winches for raising and lowering the boom for moving a trolley along the boom, and for operating a hoist on the trolley are fixedly mounted in a standard transport container at a construction site remote from the assembly site for the crane. The power supply system for the winches, including a step-down transformer and switch gear, is similarly mounted in a second container remotely from the assembly site. The two containers and their contents are lifted to the top of the erected crane tower and permanently fastened there. The winch motors are connected to the switch gear by a plug-in, multi-conductor cable, and the winches are connected with the boom, the trolley, and the hoist by steel cables or other tension elements. Labor for installing the winches and the associated electrical system is reduced and damage to the relatively sensitive machinery during assembly with other crane elements is avoided.

Abstract: A tower crane is erected from a boom assembly, first and second tower sections of different cross section, and a base in a sequence of steps in which the boom assembly is mounted on a hollow climbing section dimensioned to be received in each of the larger second tower sections and defining a cavity dimensioned to receive each of the first tower sections. One of the latter is secured on a base in upright position, and the upright section is received in the cavity of the climbing section which is then raised relative to the first section and enveloped by one of the second sections. The enveloping section is secured to the base and the raised climbing section for supporting the climbing section whereupon the first tower section may be rleased from the base, raised, and secured to the second tower section.

Abstract: The disclosure relates to laying railroad rail. The rail is placed on the unspiked tie plates of a roadbed. One end is fixed in place. Starting at the fixed end, successive sections of the rail are if necessary subjected to heat exchange to bring them to a predetermined temperature, relates to the mean ambient temperature of the locality where the rail is being laid. The necessary heating or cooling may be performed using means moved along the rail from the fixed end toward the free end. In order that rail may be laid at said predetermined temperature and while stress free, vibrations are imparted to the rail whereby any stress tending to develop in the rail from expansion or contraction, because of the temperature change, is relieved. The stress free rail at the predetermined temperature is then spiked in place and rail anchors are applied.

Abstract: This disclosure describes a drilling mast system which is adapted to be assembled section by section in a vertical position, as distinguished from the conventional method of raising a drilling mast by assemblying the mast in a horizontal position on the ground and then lifting the mast into a vertical position. The mast is made of a base section and a plurality of upper sections, each one adapted to be mounted on top of the one below it and fastened thereto. After the base section has been assembled on the foundation, the succeeding sections are assembled on the ground or are lifted in pieces and assembled in place on top of the previous section by means of a floating gin pole. The gin pole is supported inside of the mast by means of a plurality of basket cables.The sections of the mast are made of rectangular horizontal cross section. The floating gin pole extends above the top of the topmost assembled section, and can tilt to the outside of the mast, so as to lift section parts outside the mast.

Abstract: An apparatus and method for automatically replacing damaged conveyor grates which can be remotely controlled. The apparatus is disposed slightly above the empty, return side of the conveyor at the cool end, and performs its function in this maintenance area. The apparatus employs a plurality of working heads which remove the damaged grate and replace it with a new grate without interrupting conveyor motion. The working heads are suspended above the conveyor in the maintenance area by a plurality of carriages which permit the working heads to access any grate within the maintenance area. The carriages also allow the working heads to move with the conveyor during the grate replacement cycle. Although the manipulation of these heads and carriages is largely automatic, the operator can initiate, direct and observe the apparatus' movements from a remote station thereby isolating him from a hazardous environment.

Abstract: A fastener feed assembly for a tool such as a power screwdriver having a drive member such as a rotatable bit includes a base fixed to the tool and a nose assembly slidably related to the base. The nose assembly includes a workpiece engaging surface, and when the tool is moved toward the workpiece during a fastener driving operation, the base moves toward the nose assembly. A return spring separates the base and nose assembly when the tool is withdrawn away from the workpiece. A strip of fasteners is fed from a magazine along a feed path through the nose assembly with sequential fasteners located in a drive position. Normally the drive member is spaced from a fastener in the drive position. During movement of the tool toward the workpiece in a driving operation, the drive member moves into engagement with a fastener in the drive position, and then continues to move in order to drive the fastener into the workpiece. A pawl is engageable with the strip in order to advance the strip along the feed path.