Cruise Links Page
Typical Cruise Control Pressure Deactivation Switch


Cruise Brake Pressure Deactivation Switch Type F3TA 9F 924 CA
© Antony Anderson 2005

Cruise Brake Pressure Deactivation Switch
showing threaded connection to Brake Master Cylinder and aluminium clamping ring that hold switch and pressure sensing element together.

Pressure Switch Patent

US Patent  4,469, 923 September 4 1984

Cruise Deactivator Switch part disassembled
© Antony Anderson 2005

Cruise Brake Pressure Deactivation switch,
(partially disassembled)
Electrical switching Element (Inside red plastic housing)
Elastomeric sealing ring
Pressure sensing element
The three parts are held together by an aluminum clamping ring that can be seen in the left hand picture

Disassembled Cruise Brake Pressure Deactivation Switch
© Antony Anderson 2005

Cruise Brake Pressure Deactivation Switch
 (partially disassembled)

Clockwise from top left:
  • Electrical switching element (switch is normally held closed by ceramic pin in pressure sensing element
  • Pressure sensing element ( with central ceramic pin that acts on switch element: when pressure increases, pin withdraws into pressure sensor housing allowing switch contact to open)
  • Elastomeric sealing ring
Note that  the pressure sensor element has a circular fulcrum such that  as the pressure rises the outer annulus of  the pressure diaphragm  moves outward and the inner annulus moves inwards so that the ceramic pin, rather counter-intuitively, moves inwards into the housing allowing the switch to snap open.

Cruise deactivation switch disassembled
© Antony Anderson 2005

See US Patent  5,932,857 for details of Kapton film used for diaphragm

pressure element
© Antony Anderson 2005
End view of Pressure Sensing Element showing how (5) is spun over edge of (7) to hold the sub-assembly together
Pressure sensing element disassembled
(Counting  11 parts clockwise, from top left, 1 to 11.)

Parts 1 to 5 assemble as follows:  plastic disc(2) fits into (1). Steel convex disc (3) goes on top of (2) and fits into (1). (1-3) fit into underside of housing (5). ceramic pin (4) fits into hole in (5) and rests against convex surface of  (4). Other end of  pin (4) exerts pressure on switch to close it during normal operation. When pressure rises pin (4) retracts into housing (5) and opens switch.

Part (6) houses elastomer ring (7). Steel annulus (8) has a Kapton square (9) placed upon it as shown. Kapton squares (10) and  (11) are placed on (9) to form a three layer diaphragm.

Parts (1-5) are turned over so that raised centre of (1) is facing. Steel annulus (8) is placed on top of parts (1-5) so that raised centre of (1) protrudes through the hole and comes in contact with diaphragm (9). Parts (6) combined with (7) are turned over so that diaphragm (9-11) is clamped between (6+7) and steel annulus (8).  Rim  of  housing (5) is spun over edge of  (7) to hold sub-assembly together as a single unit.

NHTSA Report EA05005

Video Reports on Ford Switch fires

Video statement from the Ford Motor Company  Investigators See Link Between Ford Fires, Climate

Hot, Humid Weather Could Be Reason For More Fires In South

POSTED: 8:35 am CDT April 20, 2005


WESH.COM Home Burns Down After F-150 Catches Fire

Owner Says She Knew About Recall But Hadn't Fixed It Yet

<>POSTED: 7:14 pm EDT April 26, 2005,  UPDATED: 6:09 am EDT April 27, 2005


[More videos on this website}

Google News on Switch Fires

Photographs © Antony Anderson March 2005