McKissick M-491S Derrick Hoist Block - 3/8 to 1/2 in - 8 Ton - 10 in

Product Description

The McKissick M-491S Derrick Hoist Block is a heavy-duty single-sheave hoist block engineered for derrick and overhead lifting applications requiring reliable, high-cycle performance in oilfield, construction, and industrial environments. Rated for an 8-ton working load limit, this block is built around a 10-inch outside diameter sheave supported by a sealed tapered roller bearing, providing high radial and axial load capacity with integrated contamination protection for extended service life under demanding field conditions. The M-491S series in this configuration accommodates wire rope cable from 3/8 to 1/2 inch in diameter.

The sealed tapered roller bearing delivers superior load capacity and precise sheave alignment compared to standard bushing or ball bearing configurations, making the M-491S well suited for sustained lifting cycles and applications where bearing reliability under combined radial and axial loads is critical. The integrated seal protects the bearing from contamination by dirt, dust, moisture, and debris, reducing maintenance requirements and extending operational life in harsh oilfield and construction environments where routine servicing may be limited. The 10-inch sheave diameter provides a suitable rope bend radius for the wire rope diameter range accommodated by this block, supporting rope longevity during high-cycle hoist operations while maintaining a practical overall block profile for derrick installation.

The M-491S designation distinguishes this block from the M-491G variant within the McKissick derrick hoist block line, with both series sharing the same sealed tapered roller bearing configuration and 8-ton working load limit while accommodating different wire rope diameter ranges. This configuration accommodates the smaller 3/8 to 1/2-inch wire rope diameter range, making it suited for derrick hoist applications where smaller-diameter wire rope is specified. This block is well suited for use in oilfield derrick systems, construction gin poles, and industrial overhead lifting applications requiring a high-performance hoist block with sealed bearing protection.

Material:

Steel (body and side plates) Sealed tapered roller bearing sheave

Compatible With:

Wire rope cable, 3/8 to 1/2 in diameter

Uses:

Traveling or fixed block in derrick and gin pole rigging systems Overhead lifting in oilfield and construction environments High-cycle hoist operations requiring sealed bearing protection Industrial overhead load handling

Key Features:

8 Ton working load limit 10 in sheave outside diameter Sealed tapered roller bearing for high load capacity and contamination protection Accommodates 3/8 to 1/2 in wire rope cable Purpose-built for derrick and overhead hoist applications Sealed bearing reduces maintenance requirements in harsh field conditions McKissick M-491S series