Lapping/en: Difference between revisions

Latest revision as of 17:03, 17 March 2025

There are two types of compressed air brake system control valves : self-lapping and non-self-lapping.

Self-Lapping

The self-lapping control valves are newer. With them, the control lever application directly corresponds to the brake cylinder pressure, and is more beginner friendly. The further the lever is set in the “apply” direction, the stronger the braking application, and the further it's set in the "release" direction, the weaker the braking application. The valve automatically handles the dumping and charging of the brake pipe , in order to get to the desired cylinder pressure.

Non-Self-Lapping

The non-self-lapping control valves are older. With them, the control lever manipulates the brake pipe pressure directly, and the process is more hands-on. The lever has a few fixed positions. Two of the positions, called “release” and “service” can be thought of as adding and releasing the brake pipe pressure, respectively. The position in-between them, called “lap”, is used to maintain whatever pressure is in the brake pipe. The furthest position, called “emergency”, releases pressure at the fastest possible rate.

By controlling the brake pipe pressure, you indirectly control the cylinder pressure, and thus, brake application.

Auxiliary reservoirs are partially drained whenever brakes are applied. When brakes are then released, it takes some time for the reservoirs to be recharged. The lap position, however, functions only if the auxiliary reservoirs are full. So, to stay in full control over non-self-lapping brakes it is recommended to not release when knowing that moments later braking may be needed again. Calculated, infrequent moves are advised instead.

Monitoring

With both control valve types it is crucial to monitor the brake pipe and cylinder gauges to fully understand the current brake state.

Conflicts

In case a train contains multiple motorized vehicles their control valves are in conflict. The conflict can be even more severe if there are mixed self-lapping and non-self-lapping valves in the train. To ensure safe operation it is necessary to cutout all excess control valves, other than the one intended to be used.

@@ Line 4: / Line 4: @@
 ==== Self-Lapping ====
-Self-lapping control valves are newer. With them, the control lever corresponds to the {{pll|Air Brake System Overview|brake cylinder}} pressure, and is more beginner friendly. The further the lever is set in the “apply” direction, the stronger the braking application, and vice versa. The valve automatically handles the dumping and charging of the {{pll|Air Brake System Overview|brake pipe}}, to get to the desired cylinder pressure.
+The self-lapping control valves are newer. With them, the control lever application directly corresponds to the {{pll|Air Brake System Overview|brake cylinder}} pressure, and is more beginner friendly. The further the lever is set in the “apply” direction, the stronger the braking application, and the further it's set in the "release" direction, the weaker the braking application. The valve automatically handles the dumping and charging of the {{pll|Air Brake System Overview|brake pipe}}, in order to get to the desired cylinder pressure.
 ==== Non-Self-Lapping ====
-Non-self-lapping control valves are older. With them, the control lever manipulates the brake pipe pressure directly, and the process is more hands-on. The lever has a few fixed positions. Two of the positions, called “release” and “service” can be thought of as adding and releasing the brake pipe pressure, respectively. The position in-between them, called “lap”, is used to maintain whatever pressure is in the brake pipe. The furthest position, called “emergency”, releases pressure at the fastest possible rate.
+The non-self-lapping control valves are older. With them, the control lever manipulates the brake pipe pressure directly, and the process is more hands-on. The lever has a few fixed positions. Two of the positions, called “release” and “service” can be thought of as adding and releasing the brake pipe pressure, respectively. The position in-between them, called “lap”, is used to maintain whatever pressure is in the brake pipe. The furthest position, called “emergency”, releases pressure at the fastest possible rate.
-By control the brake pipe pressure, you indirectly set the cylinder pressure to the required amount.
+By controlling the brake pipe pressure, you indirectly control the cylinder pressure, and thus, brake application.
-Auxiliary reservoirs are partially drained whenever brakes are applied. When brakes are then released, it takes some time for the reservoirs to be recharged. The lap position, however, functions only if the auxiliary reservoirs are full. So, to stay in full control over the brakes it is recommended to not release non-self-lapping brakes when knowing that moments later braking may be needed again. Calculated, infrequent moves are preferable when operating non-self-lapping brakes.
+Auxiliary reservoirs are partially drained whenever brakes are applied. When brakes are then released, it takes some time for the reservoirs to be recharged. The lap position, however, functions only if the auxiliary reservoirs are full. So, to stay in full control over non-self-lapping brakes it is recommended to not release when knowing that moments later braking may be needed again. Calculated, infrequent moves are advised instead.
 ==== Monitoring ====
@@ Line 20: / Line 20: @@
 ==== Conflicts ====
-In case a train contains multiple motorized vehicles their control valves will conflict each other. The conflicts will be even more severe if there are mixed self-lapping and non-self-lapping types. To ensure safe operation it is necessary to {{pll|Brake Cutout|cutout}} all excess control valves, other than the one intended to be used.
+In case a train contains multiple motorized vehicles their control valves are in conflict. The conflict can be even more severe if there are mixed self-lapping and non-self-lapping valves in the train. To ensure safe operation it is necessary to {{pll|Brake Cutout|cutout}} all excess control valves, other than the one intended to be used.
 [[Category:Air Brake System|2]]