Abssac, Precision Motion Since 1982  
Abssac Newsletter : June 2013

Abssac On-The-Go

Your Flexible Friend

Does your rotary application design demand unusual shaft attachments or perhaps the design requires a higher degree of angular offset than the standard flexible shaft coupling can deliver?

Perhaps your application needs to transmit more torque, but you cannot change the physical envelope size of the existing shaft coupling?

These questions are nothing new to Abssac, who have been solving such problems for over 30 years with its unique specialist Heli-Cal beam product. As the originators of the product, the ability to adapt into applications where simply others can not follow provides the end user with a means to help solve rotational challenges, without the cost burden normally associated with special or bespoke made products.

By utilising flawless production techniques, the single piece construction totally eliminates any form of friction wear within its design, whilst also ensuring a zero-backlash and no torque loss operation.

These two shaft couplings have the same length and diameter but by changing the characteristics of the coil area they have totally different torque and angular capabilities.

The Heli-Cal product, is determined by six major characteristics:

  1. The shaft coupling outside diameter
  2. The shaft coupling inside diameter
  3. The coil thickness
  4. The material used
  5. The number of coils in the flexure area. i.e. more coils more flexibility
  6. The number of coil starts i.e. single, double or triple start

By altering these characteristics; torque capacity, angular and parallel misalignment capabilities, can be modified to suit specific specifications and or requirements.

Miniature Designs

Did you know that Abssac has just supplied a fully functional 3mm diameter shaft coupling for a medical application. Using a left and right handed thread shaft for attachment the coupling could accept up to 1 degree of angular offset rotating up to 10,000 rpm. The same customer is now looking at a double start flexure with a 1.5mm outside diameter produced in titanium.

Miniature Designs

Tel: 01386 421005  :  Email: sales@abssac.co.uk  :  Web: www.abssac.co.uk

Abssac, Precision Motion Since 1982  

Marine power transmission

Marine power transmission

Marine power transmission systems make stringent demands on shafts and clamping components. Not only must they deliver high torque capacity, but they must also offer high levels of reliability combined with ease of maintenance.

Marine power transmission systems can require frequent disassembly for maintenance, so quick mounting of dismounting is an essential feature. Then there are the challenging marine environment and the fact that there is often very little space in which to work. As yachts increase in size, outboard propulsion systems quickly become inappropriate, whilst on the very largest yachts and highest powered craft exotic propulsion systems such as water jets are becoming fashionable. But for yachts between 40 and 100 feet in length, from luxury yachts right up to the so-called super yachts, by far the most common propulsion arrangement where speeds above 40 knots are not required is the in board drive with conventional submerged propellers.

All propulsion systems have their advantages and disadvantages, but in board drive lines benefit from an inherent simplicity and, when properly maintained, a near unlimited life. The emphasis on maintenance is crucial. The underwater appendages are subject to shock and in there will always be inherent vibration.

Excessive vibration would likely indicate serious wear due to misalignment, but there is inherent misalignment in all in board propulsion systems: the engine is installed on rubber mounts and the shaft is mounted in rubber bearings, so both engine and shaft can move. In addition, the boat shaft itself is not completely rigid so there is more potential for movement.

Dismantling of the ETP-HYCON is done in the reverse way as in assembly, which also ensures an even dismantling pressure and no damage to the shafts. The ETP-HFC coating more than doubles the coefficient of friction from 0.15 (about the standard for conventional mechanical couplings) to better than 0.3. This means designers can specify a smaller shaft connection device with lower mass for any given torque requirement, making the whole assembly dynamically more efficient. Concentricity of the shaft is also maintained to a very high lateral run out tolerance.

Compact drive line couplings for high performance and low inertia

An innovative design of shaft clamp is delivering key benefits in a range of power transmission applications, not least in the highly challenging marine environment. We look at their use on the latest super yachts, and how they are delivering a new paradigm in torque transmission capability, reliability and ease of maintenance.

Shaft alignment

While it is vital that shaft coupling alignment is extremely accurate, it can be seen that it will be virtually impossible to eliminate misalignment between the shaft itself and the engine. When the engine is running, the shaft will tend to self align to a degree, but there will always be wear. Because of this, there is a need for reasonably regular maintenance to check and, if necessary, replace the rubber mounts and other key components. This makes ease of disassembly and dismounting of the propulsion system critical for a cost-effective propulsion system.

Traditional shaft clamping components fail to address all of these issues. Most mechanical shaft connections require numerous bolts; in the cramped engine and shaft tunnel, this makes the shaft a challenge to install and certainly does not facilitate easy maintenance. As well as the time and effort involved in working with so many bolts, there is also the potential to mark the shaft during assembly, which can be detrimental to the friction joint - and so impact on torque capacity - and increase the likelihood of premature corrosion.

Maintenance is further complicated by the fact that space is at a premium on yachts even of the very largest sizes, and in-board drives are often installed in areas where there is very little working space. This also impacts on power, with the torque handling capacity of a traditional coupling directly related to its physical size. So in a traditional in-board marine engine, the coupling between the engine and the shaft is one of the primary limiting factors in the maximum torque capability of the drive train.

Hydraulic shaft clamping

ETP-HYCON hydraulic shaft clamping connection couplings from Abssac offer a completely different kind of shaft connection, offering robust and compact high power transmission. Designed to deliver reliability, but also quick mounting and dismantling, the ETP-HYCON couplings are ideal for a host of applications in difficult environments and heavy operations, including challenging marine engine drives.

Used to connect shafts within a driven system, the ETP-HYCON couplings use hydraulics to create the friction seal between the shaft and the coupling. The coupling consists of a double walled hardened steel sleeve, filled with a pressure medium. The outer sleeve has two hydraulic connection points and the inner sleeve is coated with unique dry frictional substance called ETPHFC on the inside wall. In the inner sleeve, assembled cylindrical rings and seals prevent any hydraulic oil loss.

When mounting, the two hydraulic connections are pressurised simultaneously. The captivated pressured oil lubricates the contact surfaces in the axial space between the seals. This pressure initiates the movement of the outer sleeve, which is forced to linearly move a small distance because of the axial force created by the oil pressure.

The linear movement of the outer sleeve against the inner sleeve, mechanically compresses the inner sleeve to an even surface pressure on the shaft. At a set pressure calculated to both holding force and required torque transmission capability, the hydraulic hoses are disconnected and the ETP-HYCON is completely installed. A rigid and strong shaft connection has been created.

  Abssac ezine

Reduced mounting time

In contrast to other mechanical connections such as keyways or taper lock alternatives, ETPHYCON dramatically reduces mounting times as the whole clamping process is hydraulically actuated. Mounting and dismantling can be achieved in seconds, without any risk of damage to the driven shaft. ETP-HYCON

couplings are available in both shaft-toshaft (HYCON S) and shaft-flange (HYCON F) versions, and are approved by DnV for marine applications, as well as being approved by other common certification authorities including Lloyds, BAS and RINA.

They are available for shaft sizes from 50mm to 220mm. Because of their decisive advantages, these innovative couplings are becoming an industry standard in luxury and super yacht applications.

One customer in Italy building an 80m luxury yacht with two 1640kW engines needed couplings with a torque capacity of 121kNm, easily accomplished with the ETP-HYCON range and within the available size envelope. A specific requirement was approval to LR-EMEA. And couplings with a design torque of 140kNm meeting Germanischer Lloyd certification were supplied for a sailing super yacht with two 1740kW engines operating at 348rpm. Couplings with design torque of 131kNm have been supplied for a German manufactured 85m luxury yacht with two 2000kW engines.

Of course the couplings are also suitable for a host of other marine drive tasks, and have been specified around the world on naval patrol boats and training vessels, fast stand-by and rescue boats, multi-purpose vessels and even an air cushion catamaran fast attack craft.

The ETP- HYCON® ultimately this delivers some key advantages.

  • A shorter and less weight coupling connection reduces inertia but will reliably transmit the same torque compared to conventional connection drive couplings.
  • Normal length couplings with reduced surface pressure can be used on hollow shafts without re-enforcement.
  • The sliding surfaces in ETP HYCON are completely sealed, meaning no oil drainage, more environment friendly and less use of oil.
  • Mounting and dismantling is done with only one pump.
  • Quick connections and a motor pump is available.

Ex stock POWER Lead Screws & Nuts

Lead screws for medium to heavy duty industrial applications can be best supplied through our Power screws and nuts program. Continuously stocking up to 3 metre lengths of lead screw diameters of 10mm, 12mm, 16mm, 20mm, 22mm, 24mm, 30mm, 36mm, 40mm and 60mm in both right and left handed formats, are supplied in both Steel and Stainless Steel.

The screws are complimented with a large selection of round bodied flanged or non-flanged Bronze nut (SAE660 bronze) designs as well as square, hex and round steel nuts. Abssac also offers a free cut to length service on all the screws.

 

Low cost industrial class ball screws aid restoration

A quick turnaround by Abssac has aided the restoration of two pre WW11 machine tools being restored to their former glory in a local woollen mills maintenance workshop. Despite the customer being without the original dimensional drawings for the ball screws and the fact that they were very much damaged, meant that Abssac had to

rely on its extensive ball screw knowledge to satisfy the customer.

First a careful measurement of the last remaining ball screw was undertaken. It was found that the ball screw was imperially sized, with a 1.00 inch diameter by 0.250 inch lead, Gothic arch ball screw format. Abssac was able to utilise a cold rolled formed ball screw format, which were cut to a length and then machined at the ends to allow them to fit a thrust bearing to the whole assembly. The traditional square section nuts that were used by the old machines were replaced by adapted standard product range nuts and were chosen

specifically for authenticity due to their single ball return design.

The whole assembly was then low temperature black Chrome plated, which gave a corrosion resistant and exceptionally smooth and scratch resistant surface finish, hope fully giving the machine at least another 50 years of service.

Mr Peter Wright of Abssac says, “It is nice to get involved with these types of projects where we are part of a restoration. Abssac has a huge range of linear products, so 9 times out of ten we can help with these more unusual requirements”

Tel: 01386 421005  :  Email: sales@abssac.co.uk  :  Web: www.abssac.co.uk

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Semiflex® Shaft Coupling

Semiflex® Shaft Coupling

If you need a compact precision coupling with high performance you need Semiflex. The Semiflex is an extremely torsionally stiff, precision coupling that operates without radial restoring forces. Compensating for axial and angular misalignment, the coupling offers high radial misalignment capacity in conjunction with a compact design. Using a unique system of two pairs of parallel links arranged at 90° to each other, the angular synchronisation of the connected shafts always remains constant regardless of the misalignment. Examples of use for the precision all-metal couplings are in printing machines, packaging machines and in material-handling equipment.

Budget Beam
Low cost precision shaft coupling connection

Abssac at the PPMA Show in 4th-6th June 2013

Stand: G63

The PPMA Show is your best opportunity to find leaders in the industry showcasing the very best in processing & packaging machinery. Our engineers will be on hand to show you the latest products utilised in the industries machinery and equipment.

Stocked shaft couplings for pumps!

ABSSAC supplies a complete range of Hytrel® sleeves to compliment its range of Sure-Flex durable pump shaft couplings, from sizes No 5 up to No 14. Available in split design for ease of installation or in a solid format, all the sleeve sizes compliment the existing flanges in the Sure-Flex range.

Hytrel® is thermoplastic polyester elastomer, which is ideal for flex fatigue and broad use temperature (+250F/-65F). Most importantly the sleeves are then strongly resistant to tearing, flex-cut growth, creep and abrasion, making them ideal for arduous shaft coupling sleeve use. Additionally, the chemical properties of Hytrel® make it highly resistant to

hydrocarbons and many other fluids, which often quickly degrade existing rubber based coupling sleeves.

Abssac Limited
E1A The Enterprise Centre,
Enterprise Way
Evesham, Worcestershire,
WR11 1GS

Tel: +44 (0)1386 421005
Fax: +44 (0)1386 422441
Email: sales@abssac.co.uk
Web: www.abssac.co.uk

FSC Logo, 100% from well managed forests

Are you looking for a shaft coupling supplier that can supply what you want from stock ?

Budgetbeam is a brand new flexible shaft coupling addressing the requirement for a high torsional stiffness, low cost in a single piece construction. It is ideal for applications where zero backlash and constant velocity torque transmission is required. Abssac revised the basic helical beam style shaft coupling and has achieved extraordinary parameters with the new double start helical beam design. As standard all Budgetbeam models compensate for the three major shaft misalignments of angular, parallel and skewed offsets unlike lesser shaft couplings. Since the design has two equidistant flexible helical beams elements with the design, the product has excellent rational balance. Maximum rpm is rated at a staggering 10,000rpm as standard. The Budgetbeam shaft coupling is manufactured from low inertia aluminium and available in set screw or unique integral clamp shaft configuration. There are four basic blank sizes which are delivered in straight through bore diameters from 3mm to 12mm.

Ideal applications include encoder, resolver, stepper motor and small electric motor axis drives. Most importantly, by employing new production techniques allows the Budgetbeam to offer all these advantages at an extremely competitive price. The Budgetbeam shaft coupling will always be in stock due to a continuous stocking regime.

The Budgetbeam expects to go head to head with other beam, bellows or x-slot shaft coupling designs on performance, price and delivery. All budgetbeam products are also quality assured by the latest BS EN ISO9001: 2000 standard.

Abssac goes Green with company cars

With emissions as low as 89g/km, Abssac's new sales vehicles are the latest Toyota Prius dual fuel models. The 3rd Generation Toyota Prius is a full hybrid electric mid-size hatchback delivering up to 72.4mpg. The vehicles are not only environmentally friendly but also keep our costs down.

Tel: 01386 421005  :  Email: sales@abssac.co.uk  :  Web: www.abssac.co.uk

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