I recently had a chance to speak with Tim Burgess, Chairman and Managing Director of William Hackett Company, Northumberland, England, while he was visiting Houston on business. William Hackett Company is promoting their new product: the lever hoist, SS-L5 Quad Pawl. This is a hoist primarily used for when lifting equipment offshore and in subsea operations using lever hoists.
I found out from Tim that The William Hackett Company has actually done a significant amount of research on this product. It is not your standard off-the-self design. Here are some interesting features.
The materials used can be related directly to a hoists Performance Ratio. In order for a hoist to comply to the EN13157, it must achieve a factor of safety of 4:1 and be able to sustain 1500 lifting cycles at 10% over its stated Working Load Limit. These two metrics cover the hoists outright tensile strength and durability. Take the William Hackett SS-L5 subsea lever hoist with a 1.6t WLL and mass at 1.5M of 7.4KGS. Given the aforementioned requirements for both outright tensile strength and endurance the William Hackett products performance ratio of 215:1 (it lifts 215 times its own body weight) whereas other competitor products can weigh 10 – 11KGS, lift 1.5t and deliver a Performance Ratio of circa 138:1 and can be 35 – 40% heavier. In discussion with major oil companies they believe that 80% of hoisting injuries relate to the unit’s mass during the transportation and rigging phases where the human being is carrying or lifting the hoist. The lighter weight of the SS-L5 is thanks to the quality of design and materials used, and the SS-L5’s performance to weight ratio reduces the risk of injury to the user during handling such as in logistics and rigging.
SS-L5 also overcomes the current industry-norm of single use immersion hoists. Burgess highlights: “Big savings are achievable with this device. The capability of the SS-L5 to be immersed multiple times means it can significantly reduce capital investment on new hoists per mobilization by up to 80%.” Customer controlled field trials reveal this product was immersed 12 times over a 60-day period. It successfully past a rigorous multi-immersion test, inspection and operation programme witnessed and verified by DNV GL. The historic paradigm of single-use hoists, which are often used once and then discarded, is very expensive and not good practice from an environmental perspective. The use of single immersion hoists isn’t sustainable for today’s industry and is representative of an out-dated practice.
Here is the grand finale: William Hackett has introduced the world’s first quad pawl mechanism. This subject is worth expanding a bit.
Within the ratcheting system, there exists a gear with teeth on it. The job of the pawl is to ride along the outer diameter of the gear as it is being cranked, then the pawl imposes its own set of teeth on the gear to stop reverse movement. In the “Good Ole Days”, companies only used one pawl. Then, they decided that Twin-Pawls were better. But, Tim tells me that 4 pawls will guarantee that the ratchet mechanism will not slip the gear.
Fine tolerance manufacturing is critical. Manufacturing and machinery continue to deliver improved levels of product accuracy and consistency. This is especially important in the design of a hoist braking mechanism which combines multiple components. Ultimately a brake must be capable of free-wheel mode during rigging without “drag” whilst engaging the brake discs as quickly as possible when a load is engaged. What is required is the minimum possible gap with the certainty of free-wheel mode and rapid brake engagement. Most first generation hoists have a gap in free-wheel mode between the brake discs of between 1.7mm and 2mm. The William Hackett SS-L5 has a gap of 1.1mm thereby enabling the brake to engage extremely quickly. It reduces the gap between the brake discs in free-wheel mode and critically reduces the potential of foreign particle ingress between the brake surfaces which can impact the brake performance’s integrity.
William Hackett have designed this hoist to provide the highest level of safety, with increased levels of redundancy and resilience to failure. Its Quad-Pawl offset load bearing mechanism is the best in the market, and it offers enhanced operating performance compared to twin pawl products. It helps to minimise project downtime or costly delays to work scopes, providing total peace of mind for operators and marine contractors.
I think this is an interesting product. This is not a design that was developed on the fly – it took some serious engineering dollars to come up with the SS-L5 Quad-Pawl lever hoist. William Hackett revealed their new design at ADIPEC 2019, in November. For more information on the SS-L5 Quad-Pawl, please contact Jason Knights: