Metering valves cut lubricant consumption by 25 per cent

Paul Boughton
Schaeffler is now offering a range of linear recirculating roller bearings and guidance systems with special lubricant metering valves that deliver precise doses of lubricant, thereby reducing lubricant consumption by more than 25 per cent compared to standard designs, and reducing maintenance and servicing costs as well as preserving resources for the customer.

Schaeffler's RUE-E range of roller monorail guidance systems can now be fitted with special lubricant metering valves to ensure that the lubricant is precisely metered under all operating conditions, regardless of the guide's mounting position. This is made possible because of several key design factors.

First, Schaeffler uses a patented injection moulding technology to produce the saddle plate, which, in combination with the various connection options for relubrication at the front, rear and side of the carriage end, and the special design of the end pieces, ensures the lubricant is directed precisely at the rolling elements. This not only minimises relubrication quantities, but also improves the reliability of the guide and is kinder to the environment.

John Loonam, the linear product specialist at Schaeffler UK, comments: "Basically, the O rings in a standard linear guidance system are replaced with the SMDS metering valves. A paper seal is placed between the end plate and the lubrication duct, which prevents leakage of the lubricant from the ends, resulting in a reduction of more than 25 per cent in lubricant consumption compared to standard designs. Only one valve per side and rolling element loop is required and one lubrication connector per carriage."

Several years ago Schaeffler's linear technology specialists developed a relubrication and sealing component kit that contained a metering system for minimising lubricant quantities and various sealing elements. These provided optimal sealing of the lubricant duct for the standard INA-branded roller monorail guidance systems. The latest SMDS integrated metering valve option offers high reliability with only one lubrication hole per carriage, independent of the roller monorail guidance system's mounting position and operating conditions.

With conventional roller monorail guidance systems, the relubrication duct between the lubrication hole on the linear guide and the rolling elements can become empty, depending on the mounting position and operating conditions. This means more lubricant is required during relubrication to ensure reliable operation and because it takes the lubricant longer to reach its desired destination. With centralised lubrication systems, only one specific dose is provided per impulse, which can be a problem. This can lead to the lubricant arriving late in the rolling elements or, at worst, lubricant starvation. This problem is exacerbated when the guide is mounted at an angle of 90 degrees, often resulting in insufficient supply of lubricant to the upper rolling element rows. In extreme cases, this can cause damage to the rolling elements and raceway, leading to the complete failure of the linear system.

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