13-030-VEH: Fuga de aire en la válvula con los frenos liberados.

Fecha de registro	16 de agosto de 2013
Número de asunto	13-030-VEH
Nombre	Andy Chogolzadeh
Agencia	Ministry of Transportation Ontario
Dirección	311-40 Godstone RoadToronto, ON, M2J 3C7CanadaVer en el mapa (se abre en una pestaña nueva)
Teléfono	905-434-1416
Correo electrónico	[email protected]
Comité	Comité de Vehículos
Estado	Cerrado
Resumen del asunto	Estaba realizando una inspección en un camión tractor International de 1998 (sin cola) cuando me encontré con este problema. Con el motor encendido y los frenos sueltos, le pedí al conductor que aplicara los frenos. La presión parecía alcanzar un máximo de alrededor de 135 psi y, al purgarla, la presión disminuía entre 10 y 20 psi por aplicación, hasta llegar a unos 90 psi en el manómetro principal. En ese momento, se encendía la advertencia de baja presión de aire, la válvula del freno de estacionamiento se cerraba y la presión volvía a cero. Creo que el tanque principal era el único que llegaba a cero y la alarma de baja presión de aire se activaba. Al realizar la prueba de baja pérdida de aire, con el motor encendido y la presión de freno en 100 psi en el manómetro principal, el conductor aplicaba los frenos. Con los frenos aplicados, la presión se mantenía en ambos manómetros y, tan pronto como el conductor los soltaba, la presión caía a cero, la alarma se activaba y la válvula del tablero se disparaba inmediatamente. El aire se escapaba por el sello de la válvula de relé ubicada en el tercer eje del lado izquierdo.
Justificación o necesidad	Importante: esto puede crear una situación peligrosa para el conductor y los demás usuarios de la vía. Actualmente, el Código de Conducta de la OCC no contempla esta situación.
Solicitud de acción	Ante todo, agradecería una explicación sobre la causa y el efecto del problema para tenerlo claro en el futuro. Asimismo, solicito que este defecto se considere una condición que cause la inoperatividad del servicio.
Medidas adoptadas por el comité	It was explained that during an inspection being conducted, a brake system lost all of the air from the brake system during a portion of the inspection procedure, and there was no condition to use to place the vehicle OOS. During the inspection after the service brake application to inspect pushrod travel, the service brake was released and the vehicle was unable to maintain air pressure with the service brake released. Once the service brake was applied, the leak stopped. The air loss rate test on a vehicle is tested with the engine idling with the compressor running (governor cut-in) and service brake fully applied. In this particular case the leakage occurred immediately after release of the brakes and resulted in loss of all pressure in the brake system. It was explained by the brake manufacturers that this can be cause by a number of issues but most likely it could be the inlet/exhaust valve of the relay valve not sealing the supply pressure from the exhaust when released. When released, the valve is supposed to open delivery to exhaust and seal the supply from the exhaust. The same inlet/exhaust valve has to seal the exhaust when applied and opens the relay valve supply to delivery. Regardless of the reason, it was agreed that loss of air from the brake system upon brake release was felt to be an equally serious safety hazard and this condition should be reflected in the OOS criteria. Further discussion also determined that there should be a small edit made to the procedure in Step 34, to indicate that it is necessary to determine air loss with the brake applied or upon release of the service brake. The committee unanimously voted to amend the OOS criteria and inspection procedure as follows: OOSC Revision 1.a. k. Air Loss Rate If an air leak is discovered and either the primary or secondary reservoir pressure is not maintained when: (1) Governor is cut-in; (2) Reservoir pressure is between 80 – 90 psi (551 – 620 kPa); (3) Engine is at idle; and, (4) Service brakes are either fully applied or released. Level 1 Procedure Revision STEP 34 TEST AIR LOSS RATE If you detected an air leak at any point in the inspection, you should now check the vehicle’s air loss rate. Have the driver run the engine at idle, ensure brakes have been released. Observe the air reservoir pressure gauge on the dash. Have the driver put the pressure at 80 psi (at about 80 psi, most compressors should be operating). With the engine idling and the air pressure between 80 – 90 psi, instruct the driver to make a full brake application. Check the air pressure gauge after initial application and after the service brake is fully released. Air pressure should be maintained or increased. A drop in pressure indicates a serious air leak in the brake system.
Documentos de respaldo	137667658113295_valve.jpg (se abre en una pestaña nueva)

Fecha de registro

16 de agosto de 2013

Número de asunto

13-030-VEH

Nombre

Andy Chogolzadeh

Agencia

Ministry of Transportation Ontario

Dirección

311-40 Godstone RoadToronto, ON, M2J 3C7CanadaVer en el mapa

Teléfono

905-434-1416

Correo electrónico

[email protected]

Comité

Comité de Vehículos

Estado

Cerrado

Resumen del asunto

Estaba realizando una inspección en un camión tractor International de 1998 (sin cola) cuando me encontré con este problema. Con el motor encendido y los frenos sueltos, le pedí al conductor que aplicara los frenos. La presión parecía alcanzar un máximo de alrededor de 135 psi y, al purgarla, la presión disminuía entre 10 y 20 psi por aplicación, hasta llegar a unos 90 psi en el manómetro principal. En ese momento, se encendía la advertencia de baja presión de aire, la válvula del freno de estacionamiento se cerraba y la presión volvía a cero. Creo que el tanque principal era el único que llegaba a cero y la alarma de baja presión de aire se activaba. Al realizar la prueba de baja pérdida de aire, con el motor encendido y la presión de freno en 100 psi en el manómetro principal, el conductor aplicaba los frenos. Con los frenos aplicados, la presión se mantenía en ambos manómetros y, tan pronto como el conductor los soltaba, la presión caía a cero, la alarma se activaba y la válvula del tablero se disparaba inmediatamente. El aire se escapaba por el sello de la válvula de relé ubicada en el tercer eje del lado izquierdo.

Justificación o necesidad

Importante: esto puede crear una situación peligrosa para el conductor y los demás usuarios de la vía. Actualmente, el Código de Conducta de la OCC no contempla esta situación.

Solicitud de acción

Ante todo, agradecería una explicación sobre la causa y el efecto del problema para tenerlo claro en el futuro. Asimismo, solicito que este defecto se considere una condición que cause la inoperatividad del servicio.

Medidas adoptadas por el comité

It was explained that during an inspection being conducted, a brake system lost all of the air from the brake system during a portion of the inspection procedure, and there was no condition to use to place the vehicle OOS. During the inspection after the service brake application to inspect pushrod travel, the service brake was released and the vehicle was unable to maintain air pressure with the service brake released. Once the service brake was applied, the leak stopped. The air loss rate test on a vehicle is tested with the engine idling with the compressor running (governor cut-in) and service brake fully applied. In this particular case the leakage occurred immediately after release of the brakes and resulted in loss of all pressure in the brake system. It was explained by the brake manufacturers that this can be cause by a number of issues but most likely it could be the inlet/exhaust valve of the relay valve not sealing the supply pressure from the exhaust when released. When released, the valve is supposed to open delivery to exhaust and seal the supply from the exhaust. The same inlet/exhaust valve has to seal the exhaust when applied and opens the relay valve supply to delivery.

Regardless of the reason, it was agreed that loss of air from the brake system upon brake release was felt to be an equally serious safety hazard and this condition should be reflected in the OOS criteria. Further discussion also determined that there should be a small edit made to the procedure in Step 34, to indicate that it is necessary to determine air loss with the brake applied or upon release of the service brake. The committee unanimously voted to amend the OOS criteria and inspection procedure as follows:

OOSC Revision 1.a. k. Air Loss Rate If an air leak is discovered and either the primary or secondary reservoir pressure is not maintained when: (1) Governor is cut-in; (2) Reservoir pressure is between 80 – 90 psi (551 – 620 kPa); (3) Engine is at idle; and, (4) Service brakes are either fully applied or released.

Level 1 Procedure Revision STEP 34 TEST AIR LOSS RATE If you detected an air leak at any point in the inspection, you should now check the vehicle’s air loss rate. Have the driver run the engine at idle, ensure brakes have been released. Observe the air reservoir pressure gauge on the dash. Have the driver put the pressure at 80 psi (at about 80 psi, most compressors should be operating). With the engine idling and the air pressure between 80 – 90 psi, instruct the driver to make a full brake application. Check the air pressure gauge after initial application and after the service brake is fully released. Air pressure should be maintained or increased. A drop in pressure indicates a serious air leak in the brake system.

Documentos de respaldo

137667658113295_valve.jpg (se abre en una pestaña nueva)