In other oil feeders, the feed is regulated by increasing or diminishing the opening through which the steam passes from the cup to the steam pipe.
Sight oil feeders are those in which there is a glass tube or body, in which the passage of the oil can be seen as it drops.
Cylinder cocks are employed at each end of the cylinder to let out the water that condenses from the steam when admitted to a cold or partly cooled cylinder. The two cocks are usually connected together by a rod, so that both may operate together.
Cylinder relief valves are valves at each end of the cylinder to relieve the cylinder from the charges of water that sometimes enter from the boiler with the live steam.
Steam ports give a quicker admission in proportion as their length is increased, and this reduces the amount of valve travel, and are sometimes given a length equal to the diameter of the cylinder bore.
The bottoms of the steam ports are sometimes so placed as to be below the level of the cylinder bore, so as to drain off the water of condensation of the steam.
Rule to find the required area of steam port.
Multiply the area in square inches of the piston, by the number opposite to the given piston speed in the following table:
| Speed of piston in feet per minute. | Number by which to multiply the piston area. |
| 100 | 0.02 |
| 200 | 0.04 |
| 300 | 0.06 |
| 400 | 0.07 |
| 500 | 0.09 |
| 600 | 0.1 |
| 700 | 0.12 |
| 800 | 0.14 |
| 900 | 0.15 |
| 1,000 | 0.17 |
The cylinder exhaust port must be open when the valve is at the end of its travel, to an amount equal to the width of the steam port, but what this width will be in any given case depends upon the width of the bridges, the amount of the steam lap and the travel of the valve, as will be explained with reference to the slide valve.