A snatch block does two jobs: it changes the direction of a wire rope pull, and by reeving the rope back on itself it multiplies the available force. The side plates open so the rope can be dropped in mid-span rather than threaded from an end, which is what makes it practical on site. The VSBS uses a shackle head, giving a pinned connection to the anchor point rather than a hook. Thirteen sizes from a 3-inch 2 tonne block up to a 24-inch 50 tonne, in carbon steel with a minimum breaking load of four times the Working Load Limit.
Key Features
- Shackle head: A pinned connection that cannot disengage under a slack line, unlike a hook head. The right choice for anchoring to padeyes and fixed points, and for any rigging left in place.
- Opening side plates: The rope drops into the sheave without threading from an end, which is the whole point of a snatch block and saves considerable time on long ropes.
- Roller bearings from 6" upward: The 3" and 4.1/2" blocks run on a bronze bush; every larger size has roller bearings, which cut friction substantially and matter on repeated or powered pulls.
- Thirteen sizes: Sheave diameters from 3" to 24", covering wire rope from 7 mm through 38 mm.
- Sized by rope as well as load: Each block quotes a wire rope diameter range as well as a W.L.L. Both must suit, since a rope too small for the sheave groove wears rapidly and one too large will not seat.
- Carbon steel, light for capacity: The 2 tonne block weighs 4 kg, the 12 tonne 36 kg, which matters when the block has to be carried up to the anchor point.
- 4:1 minimum breaking load: Minimum breaking load is four times the marked Working Load Limit.
Technical Specifications
| Product Code |
Sheave Dia |
W.L.L. (t) |
Wire Dia (mm) |
A1 (mm) |
B (mm) |
C (mm) |
Weight (kg) |
| VSBS32 |
3" |
2 |
7–9 |
292 |
82 |
70 |
4 |
| VSBS44 |
4.1/2" |
4 |
10–12 |
358 |
120 |
70 |
6 |
| VSBS6816 |
6" |
8 |
16 |
475 |
160 |
93 |
15 |
| VSBS6820 |
6" |
8 |
19–22 |
498 |
160 |
93 |
14 |
| VSBS88 |
8" |
8 |
19–22 |
549 |
210 |
93 |
20 |
| VSBS1012 |
10" |
12 |
19–22 |
701 |
260 |
114 |
36 |
| VSBS815 |
8" |
15 |
— |
672 |
— |
— |
— |
| VSBS1215 |
12" |
15 |
— |
— |
— |
— |
— |
| VSBS1615 |
16" |
15 |
— |
— |
— |
— |
— |
| VSBS1422 |
14" |
22 |
— |
— |
— |
— |
— |
| VSBS1630 |
16" |
30 |
— |
— |
— |
— |
— |
| VSBS2030 |
20" |
30 |
— |
— |
— |
— |
— |
| VSBS2450 |
24" |
50 |
— |
— |
— |
— |
— |
All dimensions in millimetres. Full dimensional data for the larger blocks is given in the user instruction manual below. The Working Load Limit is marked on the head fitting.
4:1 Minimum Breaking Load | W.L.L. Marked on Head Fitting | LOLER Ready
Carbon steel construction with a minimum breaking load of four times the marked Working Load Limit. The W.L.L. is marked on the head fitting rather than the side plate. Supplied with test certification. Under LOLER 1998, lifting equipment requires thorough examination by a competent person at intervals not exceeding 12 months, or 6 months where used to lift persons.
Suitable Applications
Snatch blocks belong wherever a wire rope pull needs redirecting or multiplying. That covers winching and recovery work, changing the line of pull around obstacles, doubling the effective capacity of a winch by reeving back to the load, crane and derrick rigging, marine and dockside work, forestry and utility line pulling, and construction where material must be pulled rather than lifted. The shackle head version suits fixed anchor points and semi-permanent rigging; where the block is moved between anchor points frequently, the hook head version is quicker to reposition. Sizing is by both W.L.L. and rope diameter, and both must match.
More About This Product
Material handling equipment solves the problem that most manual handling injuries come from: moving something heavy a short distance. Cranes handle the long lifts; the damage is done shifting a machine six metres across a workshop because it seemed too short a distance to be worth rigging.
The equipment is straightforward. The considerations that catch people out are the floor, the route and the momentum of something heavy once it is rolling.
The Route Is the Risk
A load on wheels behaves entirely differently from a load being lifted, and the risks move with it.
Point loading comes first. Wheel loads under a laden truck or skate concentrate onto small hard wheels, and the pressure at each contact patch is far higher than the load's own footprint would suggest. Slabs that carry the static load comfortably can crack, and floor coverings can be marked or cut.
Level changes are where control is lost. A multi-tonne load rolling at walking pace and stopping abruptly against a threshold, an expansion joint or a change in floor covering keeps trying to move. Anyone with a hand on it at that moment finds out how much energy is in it. The answer is to slow down before the change, not at it.
Gradients compound the same problem. Even a slight slope in a workshop floor will accelerate a heavy load on good wheels, and a load that gets away has no brakes.
Nobody walks alongside. The instinct is to have people at the sides steadying the load, and that is exactly where they should not be if it shifts or a wheel collapses. Push or pull from a position of control, keep feet clear of the wheels, and treat the route as part of the plan rather than as the bit between the lifting points.
How to Use the Snatch Block
- Size by load and by rope: Select a block whose W.L.L. exceeds the load in the line, and whose sheave suits your rope diameter. A rope running in an oversized groove flattens; one forced into an undersized groove is crushed.
- Understand the load on the block: The force on the block is not the same as the line pull. Where the rope turns through 180 degrees the block sees roughly twice the line tension. Calculate for the actual angle.
- Anchor to a rated point: The shackle head must connect to an anchor rated for the resultant force, which as above may be double the line pull.
- Close and secure the side plates: Confirm the plates are fully closed and the retaining pin engaged before applying load. An open snatch block will throw the rope.
- Keep the rope in the groove: Check the rope is seated in the sheave before tensioning, and watch for it riding up under load.
- Keep clear of the bight: Stand outside the angle of the rope. If the block or rope fails, everything moves through that angle.
Warning: The load on the block can be up to twice the line pull depending on the angle of the rope. Never anchor a snatch block to a point rated only for the line pull. Never apply load with the side plates open or the retaining pin disengaged. Never stand within the angle of the rope.
Safety Information
- Never exceed the marked Working Load Limit, shown on the head fitting.
- Calculate the resultant load on the block, which depends on the rope angle and can reach twice the line tension.
- Match the sheave to the wire rope diameter range specified for that block.
- Confirm the side plates are closed and secured before every use.
- Do not stand within the angle formed by the rope.
- Withdraw from service any block with a cracked side plate, worn sheave groove, seized sheave or damaged head fitting.
- Do not use a snatch block with a wire rope showing broken wires, birdcaging or corrosion.
- Thorough examination by a competent person required at intervals not exceeding 12 months under LOLER 1998.
Inspection and Maintenance
The sheave groove is where a snatch block wears and where problems show first. Check the groove profile for flattening or a worn step, both of which mean the block has been run with the wrong rope size or badly worn rope. Spin the sheave by hand: it should turn freely, and any roughness or notchiness in the bearing means it needs attention before the next use. On the 3" and 4.1/2" bronze bush blocks, expect more friction by design but still smooth rotation. Check the side plates for cracking around the pivot and the retaining pin for security, and inspect the head fitting for distortion and legible marking. Lubricate the bearing and pivot regularly, particularly on blocks used outdoors.
Downloads
Frequently Asked Questions
Q: Shackle head or hook head?
A shackle head is pinned and cannot come off under a slack line, which suits fixed anchor points and rigging left in place. A hook head is quicker to move between anchor points but can disengage if the line goes slack. For recovery work where the block is repositioned constantly, hook head. For anything semi-permanent, shackle head.
Q: Why is the load on the block higher than my winch pull?
Because the block carries both legs of the rope. If the rope enters and leaves in the same direction, a 180 degree turn, the block sees roughly twice the line tension. At 90 degrees it sees about 1.4 times. This is the most commonly underestimated figure in snatch block rigging and it applies to the anchor point too.
Q: Does the wire rope size really matter?
Yes, as much as the load rating. The sheave groove is machined for a range of rope diameters. Too small and the rope flattens into the groove and wears rapidly; too large and it will not seat and can jump out. Each block in the table quotes its rope range.
Q: What is the difference between bronze bush and roller bearing?
Friction. The 3" and 4.1/2" blocks use a bronze bush, which is simple and robust but takes more effort to turn. Every size from 6" up has roller bearings, which spin far more freely. On a powered pull or repeated use, the roller bearing block wastes considerably less of your pulling force.
Q: Can I use a snatch block to double my winch capacity?
Yes, that is one of its main uses. Anchoring the block to the load and reeving the rope back to a fixed point roughly halves the required line pull for the same load, at the cost of halving the speed and doubling the rope you need. Note the block itself then sees the full load.
