McKissick M-491S Series Derrick Hoist Block - 30 Ton - 1-1/4 in Wire Rope - 20 in Sheave - Roll Forged

Description du produit

The McKissick M-491S Series Derrick Hoist Block is a heavy-duty rigging block engineered for extreme-capacity derrick and hoist applications in the most demanding industrial and oilfield environments. Rated at 30 tons, this configuration of the M-491S Series represents one of the higher-capacity offerings in the McKissick derrick block line, purpose-built for the extreme loads, continuous cycling, and harsh operating conditions encountered in large-scale derrick hoisting operations. The M-491S Series reflects McKissick's long-standing expertise in producing premium-grade hoist and derrick blocks for the most demanding segments of the rigging and lifting industry.

This block features a 20-inch sheave outside diameter and accommodates a maximum wire rope cable diameter of 1-1/4 inch. The sheave is roll forged, a manufacturing process that produces a denser, stronger grain structure compared to cast sheaves, resulting in superior resistance to wear, impact, and fatigue under the high-cycle, high-load conditions typical of large derrick hoisting service. The 20-inch sheave diameter provides an excellent D:d ratio relative to the 1-1/4 inch cable, significantly reducing wire rope fatigue and extending rope service life under the repeated heavy load cycling characteristic of continuous-duty derrick operations. The block runs on sealed tapered roller bearings, which provide excellent radial and axial load capacity, reduced friction, and extended service life, with the sealed design protecting the bearing from contamination by dirt, moisture, and other environmental factors common in oilfield and heavy industrial environments.

The M-491S Series at this capacity is designed for large-scale derrick hoist service where reliability under sustained extreme loads and high-frequency cycling is non-negotiable. The combination of a roll forged sheave, sealed tapered roller bearings, and a 20-inch sheave diameter represents a premium specification well-suited to continuous-duty hoisting applications in oil and gas, heavy construction, marine, and other industries where equipment failure is not an option and downtime carries significant operational and financial consequences. As with all high-capacity rigging hardware, proper installation, regular inspection, and strict adherence to the rated working load are essential for safe operation.

Material:

Steel construction Roll forged sheave Sealed tapered roller bearings

Compatible With:

1-1/4 in maximum diameter wire rope cable Large-scale derrick hoisting systems High-capacity industrial and oilfield rigging configurations

Uses:

Large-scale derrick hoisting operations in oil and gas environments Extreme-capacity industrial lifting and hoisting Heavy construction and civil engineering crane applications Marine and shipyard hoisting operations Continuous-duty high-cycle hoisting applications requiring maximum reliability

Key Features:

30 ton working load capacity 20 in sheave outside diameter Maximum cable size: 1-1/4 in Roll forged sheave for superior wear and fatigue resistance Sealed tapered roller bearings for high-load performance and contamination protection Reduced maintenance requirements due to sealed bearing design M-491S Series — McKissick derrick hoist block line McKissick brand — established rigging hardware manufacturer