McKissick M-491S Derrick Hoist Block - 3/8 to 1/2 in - 4 Ton - 8 in

Product Description

The McKissick Series M-491S Derrick Hoist Block is a heavy-duty block engineered for derrick hoisting and lifting applications in oilfield, construction, and industrial environments. Rated to a 4-ton working load capacity and designed to accommodate wire rope from 3/8 to 1/2 inch in diameter, the M-491S is built for reliable performance in the demanding vertical lifting cycles typical of derrick and mast hoisting systems. The 8-inch sheave outside diameter provides an appropriate rope bend radius for the wire rope sizes used in this capacity range, supporting rope integrity and consistent performance under repeated load cycles.

The Series M-491S features sealed tapered roller bearings, a bearing configuration that combines the superior load distribution of tapered rollers — capable of handling both radial and axial loads — with sealed construction that protects the bearing from contamination by dust, dirt, and moisture in harsh field environments. This sealed design significantly reduces maintenance requirements and extends bearing service life in the demanding conditions typical of oilfield and derrick operations. The sealed bearing construction makes the M-491S particularly well suited to applications where regular relubrication access is limited or impractical.

McKissick's M-491S designation reflects a purpose-built derrick hoist block designed for integration into derrick and mast hoisting systems where reliable, low-maintenance performance is essential. These blocks are commonly used in conjunction with wire rope hoisting systems on drilling rigs, service rigs, and construction derricks where controlled vertical load handling is required. All shackles, hooks, swivels, and attachment hardware used in conjunction with this block should be rated to match or exceed the 4-ton working load limit to maintain a safe and compliant hoisting assembly.

Material:

Steel construction (housing and sheave) Sealed tapered roller bearing

Compatible With:

3/8 in to 1/2 in wire rope Derrick and mast hoisting systems

Uses:

Derrick and mast vertical hoisting operations Oilfield service rig lifting applications Construction derrick load handling Wire rope hoisting system integration Industrial vertical lifting applications

Key Features:

4 Ton working load capacity 8 in sheave outside diameter Accepts 3/8 to 1/2 in maximum cable diameter Sealed tapered roller bearing for combined radial and axial load capacity Sealed bearing construction for reduced maintenance in harsh environments McKissick Series M-491S Derrick Hoist Block