Energy Recovery System (ERS) for off-highway applications will be presented at Cologne conference
Torotrak Group will present its Flybrid flywheel energy recovery system (ERS) at the Electric and Hybrid Industrial Vehicle Technology (EHIVT) Symposium in Cologne on 9-10 November. In a presentation entitled ‘High efficiency flywheel system for hydraulic energy recovery’, Steve Hughes, Torotrak Group chief operating officer, and Joanna Brahova, the company’s Business Development Director, will outline the design and development of the system.
Off-highway machines fitted with Flybrid ERS can make potential fuel savings of between 10 and 25% because the system captures energy that is normally wasted during repetitive operations. Coupled with a low on-cost, this leads to short payback times and greater profitability for end users. The use of robust mechanical technology also suits the harsh operating environment often encountered in off-highway applications, overcoming many of the challenges faced by high-voltage electric hybrids.
“A mechanical flywheel is a compact, well proven and highly efficient way to capture and release large amounts of energy very quickly,” said Hughes. “The inherently low cost of Flybrid ERS means the technology typically pays for itself within the first year of operation because of the fuel savings.”
“We understand that the off-highway industry requires a reliable and fully controllable product,” said Brahova. “Our engineers have created a system that has the ability to harvest boom energy whilst retaining perfect controllability – something that no other hybrid can currently do.”
Having developed several flywheel-based energy recovery systems across a number of industries, Torotrak Group is now working with some of the leading off-highway equipment manufacturers to help provide significant fuel savings on future off-highway vehicles. The company’s Flybrid ERS features in two engineering programs announced recently, each partially government-funded by Innovate UK through the Advanced Propulsion Centre.
The Torotrak Group presentation takes place at 16:25 on 9th November, in the conference rooms on level 4 located in Conference Centre East of the Köln Messe.
Bespoke and standard gas struts meet every need
Engineering components and parts manufacturer, WDS Component Parts Ltd. has extended its range of gas struts with new stroke lengths and options. The company can provide standard gas struts by overnight delivery or work with customers to develop bespoke units that perfectly match their application needs.
The extended range now offers stroke lengths between 20mm to 500mm. Rod and body sizes are available from 6mm rod diameter coupled with 15mm body diameter to 14mm rod with 28mm body. The actuation forces available range from 20N to 2,500N, depending on the size of the gas strut.
Each strut is fitted with an adjusting valve so that the internal pressure can be pre-set to the requirements of the application. Once the strut is installed the valve can be used to re-adjust the pressure in situ.
An extended range of end fittings are available, including clevis pin, clevis eye and angle joints. These can be fitted by WDS or supplied separately.
Carbon steel is the usual choice of construction material for the body of the gas struts, but a 316 stainless steel option is available for arduous duty applications.
Both standard and bespoke products can be ordered on line via the WDS website (www.wdsltd.co.uk), where 2D and 3D CAD drawings of the standard units are available. For bespoke struts, the site has an easy to use design wizard where users simply enter the required size, stroke length, thread and force of the spring, along with the preferred materials of construction.
Precision and skill needed to replace large rolling bearings
Replacing the extremely large rolling bearings used in steelmaking equipment poses significant challenges with regard to the tools, team and strategy deployed. However, this task is not insurmountable, as NSK recently demonstrated in the overhaul of a converter at a major Scandinavian steelworks. Here, NSK and its authorised distributor Nomo supported a Finnish gearbox manufacturer in the replacement of six tapered roller bearings featuring an inner diameter of 1800mm.-Image1.jpeg – Steel industry converters have very large bearings that are subject to high stresses
Nordic and US-based SSAB is a leading European steel manufacturer. The company is principally known for its high-strength steels, which are popular in demanding applications such as crash-related car body sections and heavy-duty construction machinery. SSAB Europe-division, manufactures high-quality strip, plate and tube products.
The entire process chain, from blast furnace to finishing, is covered by SSAB Europe´s four production sites in Scandinavia. As part of a planned maintenance project, three converter gearboxes recently had to be overhauled and equipped with new bearings at the company´s Raahe plant near Oulu, Finland. Gearbox manufacturer David Brown Santasalo was duly commissioned to perform the work, the first stage of which involved removing the gearboxes from the converter and dismantling them at its Jyväskylä factory, some 300km south.
Industry specialists from NSK inspected the bearings and checked the operating data. The Russian-made converter gearboxes were heavy and relatively old, while an added challenge was factoring in the Russian tolerance norms for the gearboxes.
After a full and detailed assessment of the application and its requirements, NSK set about developing bearings with a higher static load rating and user-specific dimensions to replace the existing tapered roller bearings. In total, six 1800mm internal diameter bearings were manufactured, weighing 2250kg each. Prior to shipping, NSK specialists devised a strategy for simultaneously installing the inner and outer ring on the gearbox sprocket wheel with the assistance of a specially designed tool.
The bearings were subsequently shipped to Jyväskylä where NSK supervised their installation using the special tool; this made it possible to adjust the bearing gap exactly.
NSK devised a formula that could define the width of the shims needed for axial bearing clearance after mounting. This had to take into account dimensions such as fixed side bearing assembled width, free side bearing assembled width, fixed side bearing inner ring width, housing diameter, and the distance of the inner ring shoulder to shaft. Following an NSK inspection sheet, each dimension was measured by David Brown Santasalo using a co-ordinate measuring machine.
After checking the measurement values and calculation, NSK was able to recommend an axial bearing clearance of 1800 to 2100µm. Both the mounting of the bearing and adjustment of axial clearance using the shim took place in the vertical position. However, the gap was adjusted again in the horizontal position due to low housing stiffness (split housing) and heavy overall weight. The top part of the gearbox housing alone weighs 11.7 tonnes, while the sprocket wheel fitted with both bearing rings weighs 11.9 tonnes. Once installed, the result (within the required tolerances) was checked by NSK technicians. NSK also asked SSAB to visit David Brown Santasalo´s site to see the mounting procedure take place.
Due to the very high torque involved in the application, the new bearings could only undergo testing after they had been installed at the steelworks. However, the refurbished converter gearboxes with the new tapered roller bearings have been operating satisfactorily under radial loads of up to 150kN.
Throughout the project, Porin Laakeri Oy Oulu part of Nomo Group provided important support services that helped ensure a successful outcome for the client and end user. Thanks to the excellent collaboration between SSAB, David Brown Santasalo, Porin Laakeri and NSK, SSAB Raahe works is now equipped with state-of-the-art converters which are more cost-efficient.
The project also demonstrated NSK´s competence in the steel industry, which is one of the company´s core target sectors. NSK rolling bearings are available to enhance all stages of the steelmaking process, from the preparation of raw material, through smelting operations, right up to the final rolled product. Applications include converters, cold and hot rolling mills, roller beds and cluster mills. Bearings for steelmaking applications feature materials that have been specially-developed by NSK to withstand high operating loads and tough environmental conditions.
The large NSK rolling bearings can be seen in this converter gearbox, which has the top part of its housing removed
The new NSK bearings being prepared for installation
Assembling one of the NSK bearing units at David Brown Santasalo
NSK´s new S-HTF ball screws made of “Tough Steel”
Newly-developed S-HTF series ball screws from NSK offer more than double the service life and 1.3 times greater dynamic load capacity than the company´s previous generation product. These performance attributes have been achieved thanks to the use of a new steel material for the screw shaft that delivers an optimised combination of hardness and resilience. Specially developed by NSK, the aptly-named ´Tough Steel´ (TF) is already being used in the company´s rolling bearings with great success.
The S-HTF ball screw has been designed for high-load applications, such as those found in plastic injection-moulding machines and forming presses. With demand for plastic products set to continue growing in coming years, component manufacturers increasingly want machines that operate with shorter cycle times and greater productivity. However, this has consequences for the electric linear drives of the clamping units. They move faster and – depending on the application – with increased clamping force, yet they are expected to last as long, if not longer than existing-generation solutions.
To meet these demands, NSK has developed S-HTF ball screws with screw shafts and nuts manufactured from TF. The high-purity of TF enables – in combination with special heat treatment – the surface of the material to be more resistant. This ensures that no cracks develop from indentations in the material caused by rolling over particles of contamination. Instead, the surface is simply ´smoothed out´ by the roll-over pressure.
Field trials at customers in Japan show that NSK´s S-HTF series high-load ball screws have a service life 2.2 times greater than its predecessor, the HTF series, along with improved load capacity.
The S-HTF series is currently available with shaft diameters from 50 to 100 mm, and leads of 10 to 60 mm (depending on diameter). Overall, there are 21 variants of the new series available. They are not only suitable for the electric clamp axes of injection-moulding machines, but for other high-load applications such as servo presses.
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