Yoke 8-551 Super Snatch Block
The 8-551 Super Snatch Block with Shackle Yoke is engineered for demanding lifting, pulling, and load-direction applications where strength, reliability, and safety are critical. Manufactured from high-quality forged steel, this snatch block delivers exceptional durability and performance in industrial, construction, marine, and recovery environments.
Designed to allow easy opening and closing, the snatch block enables quick installation of wire rope without the need to disconnect the line, reducing downtime and improving operational efficiency. The integrated shackle yoke provides a secure and stable connection point, allowing for fast attachment to anchor points, lifting equipment, or structures.
Precision-machined sheaves ensure smooth rope travel, minimising friction and wear on the wire rope while improving load control. The robust forged construction offers excellent resistance to impact, deformation, and fatigue, making it suitable for repeated use in harsh working conditions.
The 8-551 Forged Snatch Block is ideal for applications such as load redirection, mechanical advantage setups, winching operations, and general lifting tasks. Designed and tested to meet rigorous industry standards, it is a dependable solution for professionals who demand safety, efficiency, and long service life from their rigging equipment.
| Part Code | WLL tonnes | Sheave Dia. (mm) | Wire Rope Size (mm) | a (mm) | b (mm) | e (mm) | f (mm) | g (mm) | k(mm) | l (mm) | r (mm) | Mass (kg) |
| 8-551-20 | 20.0 | 203 | 25-29 | 109 | 93 | 150 | 55 | 216 | 433 | 671 | 616 | 41.6 |
| 8-551-2010 | 20.0 | 254 | 25-29 | 109 | 93 | 150 | 55 | 280 | 481 | 778 | 723 | 52.4 |
| 8-551-2012-29 | 20.0 | 305 | 25-29 | 109 | 93 | 150 | 55 | 330 | 485 | 883 | 778 | 62.8 |
| Part Code | WLL tonnes | Sheave Dia. (inches) | Wire Rope Size (inch) | a (inch) | b (inch) | e (inch) | f (inch) | g (inch) | k(inch) | l (inch) | r (inch) | Mass (lbs.) |
| 8-551-20 | 20 | 8 | 1-1-1/8 | 4.29 | 3.66 | 5.91 | 2.17 | 8.50 | 17.05 | 26.42 | 24.25 | 90.8 |
| 8-551-2010 | 20 | 10 | 1-1-1/8 | 4.29 | 3.66 | 5.91 | 2.17 | 11.00 | 18.90 | 30.60 | 28.46 | 119.0 |
| 8-551-2012-29 | 20 | 12 | 1-1-1/8 | 4.29 | 3.66 | 5.91 | 2.17 | 13.00 | 19.10 | 32.80 | 30.63 | 137.8 |
Load On Blocks
Angle Factor Multipliers
The working Load Limit (WLL) for Yoke Group blocks indicates the maximum load that should be exerted on the block and its connecting fitting. this total load value may be different from the weight being lifted or pulled by a hoisting system. it is necessary to determine the total load being imposed on each block in the system properly determine the rated capacity block to be used. A single sheave block used to change the load line direction can be subjected to total loads greatly different from the weight being lifted or pulled. The total load value varies with the angle between the incoming and departing lines to the block. the following chart indicates the factor to be multiplied by the line pull to obtain the total load on the block.
| Angle | Factor | Angle | Factor |
| 0 | 2.00 | 100 | 1.29 |
| 10 | 1.99 | 110 | 1.15 |
| 20 | 1.97 | 120 | 1.00 |
| 30 | 1.93 | 130 | 0.84 |
| 40 | 1.87 | 135 | 0.76 |
| 45 | 1.84 | 140 | 0.68 |
| 50 | 1.81 | 150 | 0.52 |
| 60 | 1.73 | 160 | 0.35 |
| 70 | 1.64 | 170 | 0.17 |
| 80 | 1.53 | 180 | 0.00 |
| 90 | 1.41 | - | - |
Sheave size and Wire Rope Strength
| Ratio A | Strength Efficiency Compared to Catalogue Strength in % | Ratio A | Strength Efficiency Compared to Catalogue Strength in % |
| 40 | 95 | 8 | 83 |
| 30 | 93 | 6 | 79 |
| 20 | 91 | 4 | 75 |
| 15 | 89 | 2 | 65 |
| 10 | 86 | 1 | 50 |
Ratio A = Sheave Diameter ÷ Rope Diameter
Strength Efficiency
Bending wire rope reduces its strength. To account for the effect of bend radius on wire rope strength when selecting a sheave, use the table above
| Ratio B | Relative Fatigue Bending Life |
Ratio B | Relative Fatigue Bending Life |
| 30 | 10.0 | 16 | 2.1 |
| 25 | 6.6 | 14 | 1.5 |
| 20 | 3.8 | 12 | 1.1 |
| 18 | 2.9 | - | - |
