Glossary “open end wrench” Definition:
A wrench with three-sided jaws on both ends.
o
open chamber head
Glossary “open chamber head” Definition:
A cylinder head in which the cylinders have no quench area.
open circuit
Glossary “open circuit” Definition:
1). Circuit in which there is a break in continuity. 2). An open circuit is any circuit that is not complete and in which no current flows.
open circuit voltage (OCV)
Glossary “open circuit voltage (OCV)” Definition:
Voltage available in a circuit, before an loads are applied.
oopen coat
Glossary “oopen coat” Definition:
Type of grit on sandpaper and discs, the resin that bonds the grit to the paper only touches the bottom of the grit.
opaque
Glossary “opaque” Definition:
Imprevious to light or not transparent, light cannot be seen through it.
one way roller clutch
Glossary “one way roller clutch” Definition:
Term used for one-way clutch or overrunning clutch.
one way sprag clutch
Glossary “one way sprag clutch” Definition:
Device that consists of a hub and drum separated by a number of sprags.
one way valve
Glossary “one way valve” Definition:
A type of switching valve that allows fluid to pass in one direction and only when the pressure is sufficient to unseat the valve
one wire system
Glossary “one wire system” Definition:
An electrical system using body and/or chassis metal as a grounded circuit.
one way clutch
Glossary “one way clutch” Definition:
1). Friction or ratcheting device that permits motion in only one direction. 2). A mechanical holding device that prevents rotation in one direction, but will overrun to allow rotation in the opposite direction. One-way clutches may be either roller or sprag clutches.
onboard system readiness test (OSR)
Glossary “onboard system readiness test (OSR)” Definition:
A function of the PCM in an OBD II system that checks the status of the various monitors.
one part putty
Glossary “one part putty” Definition:
Spot putty applied directly out of the tube or container. It takes longer to harden than two-part and can shrink more easily.
one piece oil ring
Glossary “one piece oil ring” Definition:
An oil ring having the expander and rails combined in a single part.
On-Demand Test
Glossary “On-Demand Test” Definition:
Self-test: The Key On/Engine Off (KOEO) and Key On/ Engine Running (KOER) which are technician initiated using a scan tool. Happening at the time of the test.
On-Line Automotive Service Information System (OASIS)
Glossary “On-Line Automotive Service Information System (OASIS)” Definition:
Computerized information system for service technicians.
onboard computer
Glossary “onboard computer” Definition:
Computer in a vehicle.
onboard diagnostics (OBD)
Glossary “onboard diagnostics (OBD)” Definition:
Special standardized diagnostic software and hardware system used to detect performance problems that adversely affect emissions and engine performance.
onboard fire extinguishing system
Glossary “onboard fire extinguishing system” Definition:
A fire-extinguishing system permanently installed in the driver’s compartment of a vehicle, required by most race-sanctioning bodies. Also being found on law enforcement vehicles.
OLV
Glossary “OLV” Definition:
Overfill Limiting Valve