April 2019 Design Notes

Overhung load adaptorshelp air boom applicators

Agriculture continues to improve with new technology for more precise seeding and fertilizing operations. High-efficiency air seeders and fertilizer applicators designed and manufactured by the Salford Group use Zero-Max Overhung Load Adaptors. They handle high speed and provide impeller support for the hydraulic motor and the system’s blower chamber for seeding and fertilizing.

The Salford blower assembly incorporates an Overhung Load Adaptor that connects to the system’s hydraulic motor.

Salford air boom applicators (like the 9620 or 6700 designed for John Deere and CaseIH equipment) are engineered for high rate fertilizer application, but to meet the needs of today’s precision applicators, they also need to vary application rates, quickly and accurately. The system’s blower fan must operate at a regulated high speed, according to the amount of fertilizer being applied. With a speed range up to 4,500 rpm, the Overhung Load Adaptor ensures that the hydraulic motor delivers smooth rotation to the impeller, so the blower consistently delivers the required air flow. These Salford tools handle a variety of seeds and fertilizers in a range of application rates.

Blower chamber provides seeding and fertilizing for the Salford Precision Disc Drill. It incorporates an Overhung Load Adaptor. The Overhung Load Adaptor with special mounting plate handles high speed and impeller support for operation of the hydraulic motor.

Other benefits include support for the impeller while extending motor bearing and seal lifetime. The Overhung Load Adaptor simplifies the construction of the blower mechanism as a proven solution while saving space. This configuration compares to previously using a coupling and a custom fabricated support device, which is timeconsuming and costly to produce and assemble. Also, the Overhung Load Adaptor provides a contamination barrier by separating the hydraulic motor from the blower chamber. The benefits are the hydraulic motor seals are protected, the hydraulic fluid is away from the blower chamber, and the Overhung Load Adaptor interfaces with and seals the blower chamber.

These latest model Salford fertilizer applicators incorporate the Model 200 Overhung Load Adaptor with a closed end keyseat for retaining the key when installed. Pre-greased, they have metric input and output shafts with an adaptor plate included to facilitate motor mounting. The model 200 is one of over 1,300 designs offered by Zero- Max. These designs include custom inverted bearings and multiple lubrication ports that increase the Overhung Load Adaptor’s load capacity, bearing life, and smooth system performance.

The Overhung Load Adaptor delivers smooth rotation to the impeller, so the blower delivers the required consistent air flow. The Overhung Load Adaptor provides support to the assembly and acts as a contamination barrier between the motor and blower chamber.

Designed for either face or foot mounting, Overhung Load Adaptors are available in over 50 standard models. SAE mounts available include A, B, C, D, E, and F mounts with 2 or 4 bolt mounting flanges. They are also available with many shaft variations including splined, threaded, tapered, and extended output shafts.

Manufactured to ISO 9001:2015 standards, these Overhung Load Adaptors are ruggedly built, with shafts machined from 130,000 psi stress-proof steel. All custom Overhung Load Adaptor designs include a detailed CAD approval drawing submitted before manufacture.

These Overhung Load Adaptors are also used in workboats, recycling systems, forestry shredders, road paving equipment, industrial conveyor drives, and many others where hydraulic systems require stability and shaft seal protection. FPW

Zero-Max | zero-max.com

Standard OHLA is modified with a custom mounting plate.

Tensioner cylinders’ environmentdefines hazardous

The tensioner cylinders used to support subsea productionrisers where they connect to the rig are the size of an 18-wheeler.These components are in motion 24/7, and must accommodate50-foot strokes during storms. With a cost of up to $100,000 to ferryone onshore for refitting and return it to the rig (not including lostproduction costs), it’s little wonder that rig operators insist everycylinder they install last at least 10 years.

That’s a tall order for the seals contained within the system — not only because of the wear requirements, but also due to the water glycol fluids used in offshore systems. The fluids are more environmentally friendly than oil-based HLP fluids, but they exhibit low lubricity properties, which is detrimental to many seal materials, including rubber.

Redundancy and wear-resistant materials Successfully creating a sealing system that meets the requirements of an offshore tensioner cylinder involves deep experience with systems of this type, seals and wear rings composed of high-performance materials that are compatible with water glycol fluids, and inclusion of a secondary seal.

Key considerations for the primary seal include wear life, lubricity, and fluid compatibility. A highly wear-resistant seal material is essential to ensure the seal system is leak-free for as many years as possible. However, the seal must also be able to move constantly within the water-based fluid system with as little friction as possible — and withstand the aggressive chemicals used to inhibit corrosion.

Seals composed of rubber-based materials do not perform well in these types of systems. They are prone to compression set and chemical attack, and their friction rate is higher than polytetrafluoroethylene (PTFE) or polyethelene (PE)-based seals. The primary seals in tensioner systems are typically composed of PTFE or PE variants and are the first line of defense against leakage.

The secondary seal, which must perform in dry environments for years, is typically a PTFE-based seal, due to its inherent lubricity and ability to resist wear at high temperatures. Even though the cylinders operate at ambient temperatures, the seal friction when running dry can generate heat, and the seal material must be able to resist this. In real-world environments, PTFE seals have performed very well when put to use as a secondary seal, ready to operate in an event of a primary seal leakage.

Early warning systems

Beyond the primary and secondary seals, a successful offshore hydraulic cylinder system must include robust filtration, an early warning system to alert operators to a leak, and high-performance wear rings to prevent rod deflection.

Although environmental seals with scraping elements are included in every tensioner cylinder, fluid cleanliness is essential for a long system life. Particles and sand can exist in a hydraulic system during the fabrication process. These must be filtered out to avoid damaging the primary seal. Operators with any questions regarding necessary filters or the degree of cleanliness required to avoid seal damage should consult with the seal manufacturer.

Early warning systems are in place on virtually every rig to prevent a catastrophic event. In the case of tensioner cylinders, this consists of an evacuation port with a sensor, either between the primary and secondary seals or downstream of the secondary seal. If the sealing system fails, fluid goes first into the port, which alerts the operator to the leak so the system can be shut down.

Millions of pounds of force are placed on tensioner cylinders as they work to hold the riser in place. That force creates side loads, which in turn can cause rod deflection. To prevent that deflection and the resulting metal-to-metal contact, high quality wear rings should be used to keep the rod centralized in the bore. The wear rings are made from a water- and wear-resistant fabric/ resin composite for maximum load capability and minimal wear characteristics.

There are several crucial questions offshore operators should ask about potential seal systems for tensioner cylinders:

1. What seal material is used for the primary and secondary seal? (Some old-school systems use stacks of seals to provide redundancy, but the seals are typically rubber-based and are thus prone to compression set, chemical attack, and high friction.)

2. Have the seal materials being used been tested to ensure they are compatible with the chemicals that will be used in the hydraulic fluid?

3. How long has the seal system lasted without leakage in real-world situations?

4. What level of filtration is required to ensure that seals within the hydraulic system are not damaged?

Seal selection for tensioner cylinders centers around three main criteria. First, the primary seal must be highly wear resistant, able to perform well in low lubricity water glycol fluids, and compatible with the chemicals used in the fluid. Second, the secondary seal must be able to run dry for up to 10 years without degrading to provide redundancy should the primary system fail. Third, both seals should be proven to perform as specified in real-world situations to ensure the rig operator will not incur the high cost of bringing the cylinder onshore to refit the seal system.

Contributed by Eric Bucci • Oil & Gas Segment Manager and Beth Figliulo • Fluid Power Segment Manager | Trelleborg Sealing Solutions

Trelleborg Sealing Solutions tss.trelleborg.com

Hydraulic energy chain securely guideshydraulic hoses in small spaces

Cables and two hydraulic hoses can be safely guided with the E2 hydraulic chain. This increases the service life and reduces maintenance intervals.

igus has introduced a new E2 hydraulic chain that serves as an energy and media guide even for small installation spaces on support legs.

Strong, space-saving and easy-to-install, the igus e-chain guides two hydraulic hoses in addition to power and control cables. The E2 hydraulic chain is an ideal solution for special mechanical engineering, and its use significantly reduces the costs of maintenance and downtime.

With a predefined minimum bend radius of 75 mm and total required installation hight of 255 mm, the E2 hydraulic chain can be integrated into almost any application, such as close to the base or on the side wall of support legs of mobile cranes or concrete pumps.

Support legs on many construction machines, such as concrete pumps or mobile cranes, are characterized by a large variety of models and components. The safe guidance of hydraulic hoses is crucial, because they need to be reliable under high mechanical stress and strong weather conditions. The E2 hydraulic chain provides efficient protection to internal cables and prevents torsion and bending of the hoses through the predefined minimum bend radius.

For a long time, igus has been using “extender crossbars” to create additional interior space for the guidance of hoses. For the E2/000 series and the E4.1 and E4.1L systems, extender crossbars, in addition to normal crossbars, can be used with high holding power to accommodate additional hoses with larger diameters.

The new chain provides energy and media guidance with one system. For the new E2 hydraulic chain, the concept was applied to the installation space-specific conditions of support legs on concrete pumps and mobile cranes. A one-piece, solid extender crossbar design and the heavy-duty pin/bore connection ensure high strength, even for large unsupported lengths. The extender crossbars are injection-molded directly on the side link and thus offer optimal hose guidance and stability.

It is also possible to place two hoses safely, one above the other. Since energy and hydraulics can be guided within a single hydraulic chain, the requirement for installation space is reduced. The hydraulic chain has an external width of just 41.2 mm and an external height of 57.5 mm. The predefined minimum bend radius is 75 mm. The total required installation height for the chain is only 255 mm. Thus, the E2 hydraulic chain can be integrated into almost any application, such as close to the base or on the side wall of support legs, a concrete pump or a mobile crane.

Running the cables separately from the two hydraulic hose compartments reduces the strain on the cables in the E2 carrier because hoses can be as thick as 20 mm while cables are only 5 mm thick.

Because hydraulic hoses are usually operated at extremely high pressure in dynamic applications, they are very maintenanceintensive. The E2 hydraulic chain meets this challenge in two ways: The extender crossbars and e-chain are made of tribologically optimized plastic. This reduces the abrasion and protects the hoses.

Its design also reduces wear to a minimum. Both the extender crossbars and the interior of the chain are designed to protect the hose. Rounded contours and wide and smooth contact surfaces keep abrasion and wear of the hydraulic hoses low.

The segmentation of the cable types also reduces the strain on the cables. Electrical and hydraulic guidance is completely separated by chambers. This follows the principle that cables and hoses with very different diameters should always be run separately. This is important because power or control cables have a maximum thickness of 5 mm, while the hydraulic hoses can be up to 20 mm.

Normally a clearance space of 20% is required, since hydraulic hoses expand transversely and lengthwise when pressurized. Designed to the last detail, the E2 hydraulic chain can offer freedom from maintenance. FPW

igus Inc. | igus.com