Drip-feed oilers are the most often used automatic oil lubrication system. To adjust the lubricant feed rate, the operator spins the needle valve and observes the drip rate in the flow sight. Closing the valve also halts oil flow.
Drip oilers can also be used with a cam-lock valve flow sight for more accurate metering applications for more precise metering applications. Compared to other drip oilers, they contain a sturdy polycarbonate flow sight, a significant advance over the breakable glass sights currently in use. You can buy these valves separately.