A couple of gearboxes were found leaking which prompted the Mariners’ stadium maintenance staff to reach out to Sumitomo to inspect them. It was recommended by Sumitomo’s Sales team to do a preventive inspection in order to avoid failure of the gearbox during service. The exterior of the gearbox does not show any defects other than the leakage found on a couple of units (Figure 8). The interior of the components showed only minor wear. The Cyclo reduction components (Figure 9) were found to be in an almost new condition. After over 24 years of gearbox operation, it is likely to find spalling on the eccentric cam or micro pitting on the disc lobes. In this case, none of these two failure modes was found, and the reduction components were deemed re-usable.

As for the bevel gears, no failure modes other than minor abrasion was found (Figure 10). The bevel gears usually operate at lower speeds than the Cyclo portion, so the minor wear will not represent an issue. The bevel gears were also deemed re-useable.

Aside from checking for the condition of the reduction components, it is a standard practice for Sumitomo’s Repair Team to do an overhaul of the unit. An overhaul would include the replacement of normal wear and tear items such as seals and bearings. Additionally, it was recommended to replace input and output shafts in order to avoid components with minor rust, in order to facilitate installation. Keeping your operations green As there is a global awareness over climate, companies are pushing towards reducing energy consumption to reduce carbon emissions. From the gearbox manufacturer’s side, a reliable Sumitomo gearbox, in combination with preventive maintenance practices, can result in reducing energy consumption by avoiding the manufacture and assembly of a replacement gearbox. As shown in this case study, there was no need to either replace the Sumitomo gearbox on this application, nor there was a need to remove it to repair / overhaul any gearbox in over 24 years of use. As for the driven machine, the precision required in the manufacturing of drive components can lead to longer manufacturing times and increased energy consumption. However, the use of Sumitomo's Taper Grip Bushing can help reduce the energy consumption used in manufacturing in two ways: 1. No key is required (except for a few specific applications). 2. No special driven shaft tolerance is required. As a result, commercially available shafting can be used, which removes two manufacturing operations and makes the manufacturing process more energy efficient. The installation process also affects energy consumption. Sumitomo's Taper Grip Bushing makes installation quicker and easier by providing greater clearance between the driven shaft and hollow bore, eliminating the need for special tools. Additionally, only a small amount of anti-seize paste is required for dismounting the gearbox, which makes the product more environmentally friendly (Figure 11). Finally, the use of Sumitomo's Taper Grip Bushing as an output connection reduces the failure rate and increases service time. In contrast, Keyed Hollow Bore installations have a small clearance between the hollow bore and driven shaft, which can result in fretting corrosion due to the rubbing of the driven shaft against the hollow bore. This can damage the hollow bore, driven shaft, and seals, leading to increased failure rates. Thanks to the friction operating principle of Sumitomo's Taper Grip Bushing, the hollow bore clamps onto the driven shaft, eliminating the risk of fretting corrosion and reducing the energy required to remove and replace the gearbox.

After over 24 years in service, the condition of the gearbox was deemed re-usable. Seals and bearings were replaced as it is recommended during overhaul. Input and output shafts were recommended to be replaced in order to facilitate future installations.  The long service time of the gearbox was a result of:  - A deep understanding of the application, resulting on the proper selection of the gearbox. - The excellence in maintenance practices that are reflected on the condition of the gearbox, as the reduction components are in excellent shape. Due to the high quality of the Sumitomo gearboxes, rarely, or if ever, any issue was found during the maintenance inspections. Proper selection and maintenance, in combination with high quality reduction components, are crucial for maximizing the gearbox’s service life and keeping your operations green.