page_title: FS Class E.636
section_title: Braking systems
hierarchical_section_title: FS Class E.636 / Technical details / Braking systems
caption_attribution_description: Rubinetto del freno continuo Oerlikon FV4
context_page_description: The FS E.636 is a class of Italian articulated electric locomotives. They were introduced in the course of the 1940s until the 1960s, and have been decommissioned since 2006. They have been one of the most numerous Italian locomotive group, and have been widely employed during their long career, hauling every type of train, ranging from freight to long range passenger services. Their introduction also saw the employment of some revolutionary design concepts, such as the articulated carbody and the three bogies scheme.
context_section_description: The locomotive has three kinds of brakes:
  Hand brake: manually activated by two wheels in each cab, one for each bogie, which make the brake shoes clamp against the wheel; a total of four out of six axles are braked this way.
  Locomotive air brakes (Freno Diretto or Moderabile): takes air from the main reservoir tanks, bypassing the brake pipe and directly loading the brake cylinders of the locomotive, thus braking it. It is slightly faster than the continuous brake, but brakes the locomotive only; it is not advisable to be used to brake a full, wagon-fitted train, since it can cause a "spring effect".
  Continuous, automatic air brake, used to brake the entire train.
  It is a negative-type brake and is called continuous because it extends itself through the entire train, automatic because if brake continuity is no longer present (general pipe breaks), emergency braking is automatically applied.
  On units with Breda-type valves and Oerlikon levers the brakes are graduable during braking and releasing; the working principles are the following.
  The braking system of the locomotive is formed by an array of components:
  Two kind of tanks, called "auxiliary reservoir" (serbatoio ausiliario) and "command reservoir" (serbatoio di comando).
  One or two pipes, running along the train, called "main pipe" (condotta principale, not on every E636 and generally only on passenger stock, freight cars don't have it) and "general pipe" (condotta generale, the actual brake pipe).
  A tap (the controller which is used to graduate braking).
  A particular device called "distributore", which is  divided into two chambers: one is kept at the general pipe pressure (which is variable), while the other at the command reservoir pressure (which is fixed to 5 bar (500 kPa; 73 psi), though may vary if the brakes are overloaded); in the middle there is a mobile piston.
  The brake cylinders.
  The brake rigging.
  When brakes are released, pressure in the brake pipe is about 5 bar (500 kPa; 73 psi), and 0 bar (0 kPa; 0 psi) in brake cylinders.
  To brake the train the driver, by moving the brake controller, creates a depression in a particular tank called "bariletto", which, through a series of coils creates a connection to the exterior which makes the general pipe to gradually lower its pressure to a value equal to the one present in the aforementioned tank (how fast this happens depends on train length: the longer it is, the slower this procedure will be).
  Inside the distributore the command reservoir pressure "wins" over now lower pipe pressure and thus the piston moves, creating a connection between the braking cylinders and the auxiliary reservoir (fed by the main tanks), which will then send a quantity of air to the brake cylinders proportional to the entity of the depression. The maximum pressure that can be reached into the brake cylinders on E636 is 3.8 bar (380 kPa; 55 psi), which corresponds to a pressure inside the general pipe of about 3.5 bar (350 kPa; 51 psi).
  In case of emergency braking, the brake pipe is put to direct communication with outside atmosphere, rapidly dropping pressure, and consequently making the train brake very fastly (though there isn't a variation of braking power: only the braking speed is affected).
  To release brakes, the driver makes the pressure rise in the bariletto, via the brake controller; the pressure in the brake pipe is restored (air is taken from the main reservoir tanks, and from the main pipe if present) to the value present in the bariletto.
  Inside the ditributore the brake pipe pressure wins over the command reservoir pressure and so the connection between the brake cylinders and the auxiliary tanks is modified (or cut, depending on the pipe pressure); the brake cylinders unload themselves sending their air outside until their pressure reaches a value proportional to the entity of the depression.
  When pipe pressure is 5 bar (500 kPa; 73 psi), the cylinders will unload until they are empty.
  For a faster brakes' release, it is also possible to briefly "overload" the braking system to a pressure proportional to the depres
caption: Particular of "Oerlikon" type brake lever.
exif: {"Image Make": "FUJIFILM", "Image Model": "FinePix S5600", "Image Software": "Digital Camera FinePix S5600   Ver1.00", "Image DateTime": "2008:03:02 00:45:55", "Image YCbCrPositioning": "Co-sited", "Image Copyright": "", "Image ExifOffset": "230", "Image PrintIM": "[80, 114, 105, 110, 116, 73, 77, 0, 48, 50, 53, 48, 0, 0, 2, 0, 2, 0, 1, 0, 0, 0, 1, 1, 0, 0, 0, 0]", "EXIF ExposureTime": "1/45", "EXIF FNumber": "5", "EXIF ExposureProgram": "Program Normal", "EXIF ISOSpeedRatings": "200", "EXIF ExifVersion": "0220", "EXIF DateTimeOriginal": "2008:03:02 00:45:55", "EXIF DateTimeDigitized": "2008:03:02 00:45:55", "EXIF ComponentsConfiguration": "YCbCr", "EXIF CompressedBitsPerPixel": "4", "EXIF ShutterSpeedValue": "11/2", "EXIF ApertureValue": "23/5", "EXIF BrightnessValue": "58/25", "EXIF ExposureBiasValue": "0", "EXIF MaxApertureValue": "17/5", "EXIF MeteringMode": "Pattern", "EXIF LightSource": "Unknown", "EXIF Flash": "Flash fired, compulsory flash mode", "EXIF FocalLength": "63/10", "EXIF FlashPixVersion": "0100", "EXIF ColorSpace": "sRGB", "EXIF ExifImageWidth": "2592", "EXIF ExifImageLength": "1944", "EXIF FocalPlaneXResolution": "4442", "EXIF FocalPlaneYResolution": "4442", "EXIF FocalPlaneResolutionUnit": "3", "EXIF SensingMethod": "One-chip color area", "EXIF FileSource": "Digital Camera", "EXIF SceneType": "Directly Photographed", "EXIF CustomRendered": "Normal", "EXIF ExposureMode": "Auto Exposure", "EXIF WhiteBalance": "Auto", "EXIF SceneCaptureType": "Standard", "EXIF Sharpness": "Normal", "EXIF SubjectDistanceRange": "0"}