Why “SNATCH” blocks?
The snatch block is one of today’s most widely used types of blocks. As generally applied, its title refers to that group of intermittent-service blocks which quickly attache and “snatch” or move loads over relatively short distances. This is opposed to long lifts and continuous service for which crane and construction blocks are designed.
Gunnebo Johnson produces a wide variety of multipurpose snatch blocks.
Over 235 models of single and double sheave snatch blocks are offered. Capacities range from 2 to 30 metric tons; sheave diameters, from 3 through 24 inches. Custom designs and sizes available also.
Only top grade materials are used for each component:
- Plates: Structural quality carbon steel to ASTM-A36/A572.
- Sheaves: Range from cast ductile iron, cast steel, or ForgeFab™ steel units with flame-hardened grooves (sizes 16 inches Outside Diameter and over).
- Hooks: Drop Forged alloy steel, quenched and tempered.
- Shackles: Alloy steel, heat treated, with heat treated and tempered carbon or alloy steel pins.
- Eyes: Carbon steel forged and heat treated.
- Center Pins: AISI 1018/1045 cold finished carbon steel.
- Latch Pins: AISI 1040 cold finished or stress proof carbon steel.
Gunnebo Johnson snatch blocks have the convenient side opening feature.
This is true even on our heavy-duty top dead-end models, and makes it easy to reeve the block without removing any fittings from the end of the wire rope. Other features include choice of swivel hook, shackle, or tailboard blocks, which have no fittings at all.
Note that a snatch block’s wire rope-to-sheave diameter ratio is not the same as that recommended for crane and construction blocks. Since the height and frequency of the lift is not as much of a factor, larger sheaves are not as crucial to snatch block operations. However, provisions should be made to increase sheave size where the situation demands. Naturally a large sheave is an advantage insofar as bearing life and wire rope life are concerned.
Note also that the lower fittings on snatch blocks 2 through 20 tons are not equipped with thrust bearings. They will not swivel as well under load.