A sprocket for a crawler undercarriage comprises a plurality of sprocket teeth for engagement with a crawler track, wherein the sprocket teeth are arranged in a plurality of similar circumferential segments along the sprocket, and wherein an odd number of circumferential segments is provided.

A mobile crane includes a main body and extendable axles, which are selectively re-positioned relative to the main body through strategically positioned apertures. The axles may be automatically locked to the main body in a desired one of the multiple positions without operator intervention. The axles one or more tapered ends for connecting to side frames, which may support crawler tracks. The tapered ends of the axles extend through openings located in the frames such that they are removably connected to an outside or exterior portion of the frames relative to the main body.

A mobile crane includes a main body and extendable axles, which are selectively re-positioned relative to the main body through strategically positioned apertures. The axles may be automatically locked to the main body in a desired one of the multiple positions without operator intervention. The axles one or more tapered ends for connecting to side frames, which may support crawler tracks. The tapered ends of the axles extend through openings located in the frames such that they are removably connected to an outside or exterior portion of the frames relative to the main body.

A multi-tower linkage type aerial hoisting platform includes: four tower crane body lifting/lowering parts respectively disposed in an outer periphery of a building to form a rectangle through enclosure, and including a tower crane body and a self-climbing lifting/lowering system that is capable of climbing or descending step by step along the tower crane body; four tower-crane-body-connected support beams, respectively disposed on two opposite self-climbing lifting/lowering systems, where a hoisting platform enclosed by the tower-crane-body-connected support beams is driven by the self-climbing lifting/lowering systems to move up and down synchronously; and four movable tower crane bases, respectively disposed at lower ends of the four tower crane body lifting/lowering parts, including movable chassis that are used as movable supports with a variable platform angle and support parts disposed on the movable chassis, where four corners of the support parts are respectively provided with rotary drilling fastening parts.

A multi-tower linkage type aerial hoisting platform includes: four tower crane body lifting/lowering parts respectively disposed in an outer periphery of a building to form a rectangle through enclosure, and including a tower crane body and a self-climbing lifting/lowering system that is capable of climbing or descending step by step along the tower crane body; four tower-crane-body-connected support beams, respectively disposed on two opposite self-climbing lifting/lowering systems, where a hoisting platform enclosed by the tower-crane-body-connected support beams is driven by the self-climbing lifting/lowering systems to move up and down synchronously; and four movable tower crane bases, respectively disposed at lower ends of the four tower crane body lifting/lowering parts, including movable chassis that are used as movable supports with a variable platform angle and support parts disposed on the movable chassis, where four corners of the support parts are respectively provided with rotary drilling fastening parts.

A multi-tower linkage type aerial hoisting platform includes: four tower crane body lifting/lowering parts respectively disposed in an outer periphery of a building to form a rectangle through enclosure, and including a tower crane body and a self-climbing lifting/lowering system that is capable of climbing or descending step by step along the tower crane body; four tower-crane-body-connected support beams, respectively disposed on two opposite self-climbing lifting/lowering systems, where a hoisting platform enclosed by the tower-crane-body-connected support beams is driven by the self-climbing lifting/lowering systems to move up and down synchronously; and four movable tower crane bases, respectively disposed at lower ends of the four tower crane body lifting/lowering parts, including movable chassis that are used as movable supports with a variable platform angle and support parts disposed on the movable chassis, where four corners of the support parts are respectively provided with rotary drilling fastening parts.

A multi-tower linkage type aerial hoisting platform includes: four tower crane body lifting/lowering parts respectively disposed in an outer periphery of a building to form a rectangle through enclosure, and including a tower crane body and a self-climbing lifting/lowering system that is capable of climbing or descending step by step along the tower crane body; four tower-crane-body-connected support beams, respectively disposed on two opposite self-climbing lifting/lowering systems, where a hoisting platform enclosed by the tower-crane-body-connected support beams is driven by the self-climbing lifting/lowering systems to move up and down synchronously; and four movable tower crane bases, respectively disposed at lower ends of the four tower crane body lifting/lowering parts, including movable chassis that are used as movable supports with a variable platform angle and support parts disposed on the movable chassis, where four corners of the support parts are respectively provided with rotary drilling fastening parts.

Dynamic energy transfer (DET) systems are costly and time-consuming to install. Accordingly, an installation system is disclosed that comprises stowage for rail segments and poles, two strategically positioned cranes, and/or strategically positioned platforms, to enable less expensive and faster installation of the various components of a DET system. Installation, utilizing the installation system, can significantly decrease the cost of installation, while increasing the rate of installation and maintaining safety.

Dynamic energy transfer (DET) systems are costly and time-consuming to install. Accordingly, an installation system is disclosed that comprises stowage for rail segments and poles, two strategically positioned cranes, and/or strategically positioned platforms, to enable less expensive and faster installation of the various components of a DET system. Installation, utilizing the installation system, can significantly decrease the cost of installation, while increasing the rate of installation and maintaining safety.