Speed describes how fast something moves. Position describes where it is. On an engine, one sensor system can provide information used for both, which is why catalogue names do not always divide neatly into 'speed sensor' and 'position sensor'. For a parts buyer, the monitored component and approved part reference are more dependable than the shorter product name.
The names can overlap
A crankshaft sensor can provide information about rotational speed and crankshaft position. Bosch's crankshaft speed-sensor information describes that connection. A listing using 'speed' and another using 'position' may therefore be describing the same function. The wording alone neither confirms nor disproves a match.
A camshaft sensor supplies a different reference. Bosch describes the engine control unit using it to establish camshaft position in its camshaft sensor explanation. That product example shows the principle; it does not identify the correct sensor for every diesel engine or imply that a crankshaft and camshaft sensor are interchangeable.
Ask what moves past the sensor
Replace a vague description with the monitored component: crankshaft, camshaft, transmission shaft or another identified rotating assembly. If the request concerns a position sensor on a linkage or control input, say so. A linear or angular position application should not be placed in an engine-speed enquiry simply because the connector looks similar.
The equipment documentation may identify a target wheel or reference feature as part of the sensing arrangement. That relationship matters because a sensor is selected for an application, not just for a hole in the housing. The description should connect the sensor to its target and controller input without guessing dimensions or setting values.
For a workshop message reading 'speed sensor by the engine', ask which assembly the sender means. An installed-location record may settle that question before any catalogue search. If the component is already loose, do not assign it a location based on its shape. Record the location as unknown until there is supporting evidence.
Keep the required result clear as well. A reading in rpm describes rotational speed; it does not, on its own, provide the positional reference a controller may need for another function.
Electrical technology is a separate check
Inductive and Hall-effect designs are among the technologies used in rotational sensing. Their operating requirements and outputs differ. Confirm the specified sensor type and electrical interface through the manufacturer reference for the application. A general explanation of a sensing technology is not a substitute for the correct replacement specification.
Pin count is not a reliable shortcut for deciding the entire technology or function. Likewise, a magnet visible near a sensing tip does not establish compatibility. Request the part-specific supply, output and connection information when an alternative is offered, and have those requirements checked against the receiving system.
Air-gap requirements and mounting geometry also belong to the particular sensor and target arrangement. Do not borrow a clearance figure from a sensor that merely resembles the required item. This is a selection check: it does not call for repositioning a sensor or altering the machine to make a proposed substitute fit.
Comparing two plausible candidates
If a supplier returns a crankshaft item and a camshaft item for the same enquiry, ask for the application reference behind each. Keep the two offers on separate lines with their stated function. Combining them under 'engine sensor' makes it harder to see that they may answer different requirements.
A useful comparison includes the monitored component, manufacturer part reference, sensing technology where documented, connector assignment and approved installation dimensions. Mark an unanswered field as unconfirmed. An attractive price does not resolve a missing application reference.
For Cummins equipment, begin with the engine identity and the Cummins parts category. For CAT equipment, use the CAT parts category. In either case, carry the exact component description into the enquiry. 'Crankshaft sensor identified in the engine record' gives the supplier a more definite task than a general request for any matching speed sensor.
