Crosby Blocks
Rigging blocks redirect wire rope and synthetic rope through a pulley for line pulls, crane fall lines, and material handling setups. Snatch blocks allow mid-line rope reeving without threading from the end. Crosby's forged block line covers both applications with sheave geometry matched to wire rope and fiber rope diameters across the WLL ranges used in industrial and marine rigging.
About Crosby Blocks
Crosby rigging blocks use a sheave (wheel) mounted in a forged steel frame to redirect wire rope or fiber rope through a change-of-direction point. The sheave groove geometry is matched to rope diameter, a mismatch between rope diameter and sheave groove produces uneven wear and can flatten the rope or deform the sheave over time.
Snatch blocks open at the side to accept rope mid-line without threading from the end. That feature is what makes them practical for field rigging setups where the rope is already in place and needs to be redirected through an added block. Crosby snatch blocks use the same forged frame and sheave construction as their standard rigging blocks.
Crosby blocks are governed by ASME B30.26-2015 (Rigging Hardware), which covers design factors, marking requirements, and inspection intervals for rigging hardware in overhead service.
Holloway Houston stocks Crosby rigging blocks and snatch blocks in Houston with same-day shipping on in-stock models.
Types of Crosby Blocks
Snatch Blocks
Crosby snatch blocks use a side-opening frame that accepts rope mid-line for directional changes and mechanical advantage setups. The opening latch is secured against the block body during use, it's a load-rated latch, not a convenience feature. Crosby snatch blocks are available in wire rope and fiber rope configurations with WLL ratings across standard rigging capacity ranges.
Wire Rope Blocks
Wire rope blocks have fixed frames and sheave grooves profiled for wire rope diameters. They're used in crane fall lines, multi-part block-and-tackle arrangements, and line-pull rigging setups where rope reeving is done before the system is put under load. Crosby wire rope blocks cover light through heavy-duty capacity ranges.
Fiber Rope Blocks
Fiber rope blocks use sheave grooves profiled for synthetic rope diameters, larger groove radius, smoother surface, to prevent wear on the rope jacket. Used in marine applications, theatrical rigging, and field applications where synthetic rope is specified instead of wire rope.
Crosby Block Sizes and Working Load Limits
Crosby blocks cover WLL ranges from light rigging and marine work through heavy industrial crane applications. Sheave size, rope diameter rating, and WLL vary by model, Crosby's catalog data is the reference for specific model specifications.
Rope Diameter Range :
- Wire rope blocks: Sheave grooves matched to standard wire rope diameters.
- Fiber rope blocks: Sheave grooves sized for synthetic rope diameters.
Materials :
- Forged steel frame, alloy steel sheave.
- WLL and manufacturer markings per ASME B30.26-2015 (Rigging Hardware).
Why Crosby for Blocks
Crosby blocks are specified across offshore, crane, and industrial rigging programs because the forged frame and alloy sheave construction handle the combined tension and bending loads that rigging blocks see in regular service. The ASME B30.26-2015 (Rigging Hardware) compliance and WLL markings satisfy documentation requirements for equipment registers.
The snatch block's side-opening latch is a load-rated component on Crosby models, the latch is not just a rope-entry convenience but part of the rated load path geometry. That distinction matters for applications where the block sees tension through the connection point.
Holloway Houston also offers rigging inspection services. Our qualified inspectors examine blocks and rigging hardware per ASME B30.26-2015 (Rigging Hardware) and OSHA standards.
Shop Crosby Blocks by Type
Crosby Block Applications by Industry
- Offshore and Marine : Fall blocks on crane systems, deck winch line redirects, and mooring system lead blocks where wire rope rigging capacity and traceability are required.
- Oil and Gas : Line pulls on workover rigs, tubing handling, and maintenance rigging in plant environments where mechanical advantage setups are common.
- Construction Rigging : Crane fall lines, gin pole setups, and directional pulls on structural steel erection and civil construction projects.
- Mining : Hoist systems, skip lines, and surface rigging where wire rope blocks see continuous cycling under load.
- Marine and Shipbuilding : Ship's tackle, deck crane falls, and mooring system hardware where blocks are a standard component of the rigging inventory.
Why Holloway Houston for Crosby Blocks
Holloway Houston is an authorized Crosby distributor with over 65 years in rigging and lifting, operating from Houston, Texas. We stock Crosby rigging blocks alongside shackles, wire rope clips, and the full Crosby hardware line.
Our rigging specialists can help match block sheave size and WLL to the rope diameter and capacity in your rigging setup. We also offer rigging inspection services.
Complete Your Block Rigging Setup
- Crosby Shackles : Anchor shackles for connecting blocks to structural connection points and crane hooks.
- Crosby Sheaves : Replacement and custom sheaves for wire rope and block systems.
- Crosby Swivels : Swivels for block assemblies where load rotation needs to be absorbed above the block.
Block Safety and Awareness
Rigging blocks in load-handling service fall under ASME B30.26-2015 (Rigging Hardware). OSHA 1926.251 references rigging hardware in jobsite use.
Key awareness points for rigging blocks in service:
- The sheave groove diameter is matched to a specific rope diameter. A rope that's too large for the groove rides on the groove shoulders; a rope too small for the groove can jump track under load or cause uneven wear on the rope.
- Snatch block latches are load-rated components. A latch that doesn't close fully or has visible deformation warrants removal from service before the block is placed under load.
- Pre-use inspection covers the sheave for cracks and groove wear, the frame for deformation, the bearing or bushing for smooth rotation, and the shackle or attachment point for condition.
- Per ASME B30.26-2015 (Rigging Hardware), blocks are marked with WLL and manufacturer identification. A block without legible markings is not suitable for rated lifting service.
Frequently Asked Questions
A standard rigging block has a fixed frame, rope must be threaded from one end of the rope assembly to reeve it through the block. A snatch block has a hinged or swing-open side that allows rope to be placed into the sheave groove mid-line without threading from the end. Snatch blocks are the standard choice when redirecting a rope that's already rigged or under light tension.
ASME B30.26-2015 (Rigging Hardware) covers rigging blocks in load-handling service, including design factors, WLL marking, and inspection requirements. OSHA 1926.251 references rigging hardware inspection in jobsite settings.
Holloway Houston stocks Crosby rigging blocks and snatch blocks in Houston with same-day shipping on in-stock models. Call 1-888-496-4700 to confirm availability on a specific block type, rope diameter, and WLL.
The sheave groove is profiled to a specific rope diameter. Using a rope that's significantly larger than the sheave groove causes the rope to ride on the groove shoulders rather than seated in the groove, which accelerates rope wear and can cause the rope to jump the sheave under load. Crosby's catalog data provides sheave size-to-rope diameter compatibility for each block model.
DISCLAIMER
Rigging blocks are load-bearing hardware. Selection, inspection, and use call for training consistent with ASME B30.26-2015 (Rigging Hardware) and applicable OSHA standards. The information on this page is provided for general product awareness and does not replace qualified engineering judgment, manufacturer documentation, or site-specific rigging procedures.