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Extensive revision of first paragraph to provide more detailed explanation. Moved one sentence to "Common applications" section. Put "internally relieved bolt" in proper location - such a bolt is only part of a banjo connection, as explained.
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[[File:Banjo_bolts.jpg|thumb|A pair of banjo bolts as used in automotive braking.]]
[[File:Banjo_bolts.jpg|thumb|A pair of banjo bolts as used in automotive braking.]]


A '''banjo fitting''' or '''internally relieved bolt''' is comprised of a perforated hollow [[screw|bolt]] and spherical union for [[fluid]] transfer.<ref name="Erjavec" /> They are commonly found in [[automotive fuel]],<ref name="Mavrigian" /> [[motor oil]] and [[hydraulic system]]s (e.g.: [[brakes]] and [[clutch]]). The pipe connected may be either rigid or a flexible [[hose]].<ref name="Erjavec" />
A '''banjo fitting''' is comprised of a perforated hollow [[screw|bolt]], or an '''internally relieved bolt''', and a spherical union for [[fluid]] transfer, typically used to connect a fluid line to a rigid, internally [[Screw_thread|threaded]] hydraulic component. The bolt is assembled through center the union, usually with [[face seal|face seals]] on either side of the union, to create a fluid path between the external ports on the union and bolt. A flexible [[hose]] or a rigid [[Pipe_(fluid_conveyance)|pipe]] may be connected to the union port.<ref name="Erjavec" />


The main advantage of the fitting is in [[high pressure]] applications (i.e. more than 50 [[Bar (unit)|bar]]). The name stems from the shape of the fitting, having a large circular section connected to a thinner pipe, generally similar to the shape of a [[banjo]].<ref name="Erjavec">{{cite book |last1=Erjavec |first1=Jack |title=Automotive Brakes |date=2003 |publisher=Cengage Learning |isbn=1401835260 |pages=144}}</ref>
The main advantage of the fitting is in [[high pressure]] applications (i.e. more than 50 [[Bar (unit)|bar]]). The name stems from the shape of the fitting, having a large circular section connected to a thinner pipe, generally similar to the shape of a [[banjo]].<ref name="Erjavec">{{cite book |last1=Erjavec |first1=Jack |title=Automotive Brakes |date=2003 |publisher=Cengage Learning |isbn=1401835260 |pages=144}}</ref>
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==Common applications==
==Common applications==

Banjo fittings are commonly found in [[automotive fuel]],<ref name="Mavrigian" /> [[motor oil]] and [[hydraulic system]]s (e.g.: [[brakes]] and [[clutch]]). General applications include:

* [[Fluid power|Hydraulic power]] systems
* [[Fluid power|Hydraulic power]] systems
* [[Power steering]] fluid
* [[Power steering]] fluid

Revision as of 23:57, 11 April 2022

An example of typical banjo fitting components (left) with an identical fitting connecting a hose to a tee fitting.
An example of typical banjo fitting components (left) with an identical fitting connecting a hose to a tee fitting.
A general schematic, not to scale, showing the fluid path in an assembled banjo fitting.
A general schematic, not to scale, showing the fluid path in an assembled banjo fitting.
A pair of banjo bolts as used in automotive braking.

A banjo fitting is comprised of a perforated hollow bolt, or an internally relieved bolt, and a spherical union for fluid transfer, typically used to connect a fluid line to a rigid, internally threaded hydraulic component. The bolt is assembled through center the union, usually with face seals on either side of the union, to create a fluid path between the external ports on the union and bolt. A flexible hose or a rigid pipe may be connected to the union port.[1]

The main advantage of the fitting is in high pressure applications (i.e. more than 50 bar). The name stems from the shape of the fitting, having a large circular section connected to a thinner pipe, generally similar to the shape of a banjo.[1]

Two banjo fittings atop automotive brake calipers. The copper crush washer in the gap between the fitting and body of the caliper completes the seal.

Compared to pipe fittings that are themselves threaded, banjo fittings have the advantage that they do not have to be rotated relative to the host fitting. This avoids damage that can be caused by twisting the hose during installation. It also allows the pipe exit direction to be adjusted relative to the fitting, then the bolt tightened independently.

Common applications

Banjo fittings are commonly found in automotive fuel,[2] motor oil and hydraulic systems (e.g.: brakes and clutch). General applications include:

References

  1. ^ a b c Erjavec, Jack (2003). Automotive Brakes. Cengage Learning. p. 144. ISBN 1401835260.
  2. ^ a b Mavrigian, Mike (2008). High Performance Fasteners and Plumbing: A Guide to Nuts, Bolts, Fuel, Brake, Oil and Coolant Lines, Hoses, Clamps, Racinghardware and Plumbing Techniques. Penguin. pp. 12–14. ISBN 978-1-55788-523-4. Retrieved September 15, 2020.
  3. ^ LaCourse, Jon; Haynes, John Harold. Chevrolet Nova & Geo Prizm Automotive Repair Manual. Haynes Publishing Group. p. 49. ISBN 978-1-85010-642-5. Retrieved September 15, 2020.