Sep 17, 2026Applications
Locating & Indexing Components for Machine & Equipment Positioning
A practical guide to locating and indexing components for machine positioning, covering fixed and adjustable positions, lock-out functions, mating interfaces, access and repeatability.
Locating & Indexing Components for Machine & Equipment Positioning
Machine and equipment positioning often involves a simple requirement that becomes difficult in practice: a movable or adjustable element must return to the intended position and remain there during use.
Examples include adjustable stops, guides, sliding assemblies, rotating elements, machine attachments and removable components.
The right solution depends on whether the position is fixed, repeatedly adjustable or temporarily released. It also depends on how the component is operated, what forces can act on the mechanism and how frequently the position changes.
This guide explains the main questions to review when selecting locating and indexing components for machine and equipment positioning.
1. Start with the required type of position
Before selecting a pin or plunger, define how the machine element is expected to move.
There are three common requirements.
Fixed position
Two components need to return to a defined relationship after assembly or removal.
A locating pin and mating locating feature may be appropriate when the main requirement is establishing a repeatable reference.
Multiple predefined positions
A movable component needs to stop at several known positions.
An indexing plunger can engage corresponding holes or locating features so the mechanism returns to predefined positions without repeated measurement.
Free movement followed by repositioning
The component must move freely through part of its travel and then be positively located again.
This may require an indexing mechanism that can remain disengaged temporarily.
Defining which of these movements is required is more useful than starting with a catalog component.
2. When should an indexing plunger be used?
Indexing plungers are particularly useful where a moving machine component must be repeatedly positioned and positively engaged.
Typical applications include:
- adjustable machine stops;
- sliding guides;
- height adjustments;
- rotating or swivelling mechanisms;
- movable brackets;
- machine attachments;
- adjustable equipment elements.
KIPP describes indexing plungers as components that allow moving machine parts to be adjusted quickly and specifically identifies swivelling or rotating devices and positioning of stops as applications. Its technical information also identifies length, height and position indexing in machines and equipment.
The key distinction is that the plunger engages a defined mating feature.
It is therefore different from relying only on friction to hold an adjustment.
3. Positive indexing or friction locking?
This distinction matters.
A friction-based clamp can hold a movable element at many positions, but the final position depends on where the operator stops and clamps it.
A positive indexing system uses a pin engaging a corresponding hole or feature to establish a predefined position.
Think of the difference as:
Continuous adjustment
→ position can be selected anywhere within a range.
Indexed adjustment
→ position returns to predefined locations.
Neither approach is automatically better.
The correct choice depends on whether the machine requires continuous adjustment or repeatable discrete positions.
Some mechanisms combine both concepts, but the positioning and holding functions should still be understood separately.
4. Consider the forces acting on the indexed position
A positioning component should not be selected only by checking whether its pin fits the mating hole.
Review what happens after engagement.
Questions include:
- What forces can act on the moving element?
- Are significant lateral forces present?
- Is the plunger establishing position, retaining the element, or both?
- Is additional clamping required?
- Could vibration or machine movement affect the interface?
KIPP specifically describes indexing plungers as useful where unintended changes in locking position due to lateral forces should be prevented; changing to a new indexed position requires disengaging the pin.
However, that does not mean every indexing plunger should be treated as a structural load-bearing pin.
The actual load capacity and allowable forces depend on the specific component and installation.
Where significant loads are involved, verify the product data and consider whether separate clamping or load-supporting features are required.
5. When is a lock-out function useful?
In some machines, the plunger should automatically engage when the next indexing position is reached.
In others, the pin needs to remain retracted while the machine element moves through several positions.
That is where a lock-out or rest-position indexing plunger can be useful.
JW Winco, for example, describes lock-out indexing plungers in which the knob is pulled and rotated so the plunger remains in the retracted position.
Consider a lock-out function when:
- the mechanism must pass several indexing holes;
- adjustment requires free movement over a longer distance;
- the operator needs both hands during repositioning;
- repeated engagement during travel is undesirable.
A non-lock-out version may be preferable when automatic re-engagement is required.
The selection should follow the intended operating sequence.
6. Prevent unintended disengagement where necessary
There is another requirement that should not be confused with lock-out:
preventing the plunger from being accidentally retracted.
These are opposite functions.
A lock-out feature keeps the pin retracted when desired.
A safety-lock feature can help prevent unintended retraction while the pin is engaged.
JW Winco offers safety indexing designs specifically for applications where inadvertent retraction of the plunger pin needs to be prevented. Elesa+Ganter likewise lists indexing plungers with safety devices intended to prevent accidental movement of the quick-release mechanism.
This distinction matters in machine design.
Before selecting the mechanism, determine whether the application needs:
automatic engagement,
temporary disengagement, or
protection against accidental disengagement.
7. Review the mating interface
The indexing plunger is only one half of the positioning system.
The pin engages a hole, slot, bushing or other mating feature. Its geometry and condition influence how consistently the mechanism locates.
Review:
- mating-hole diameter;
- pin diameter;
- alignment between the plunger and mating feature;
- engagement depth;
- edge condition and lead-in;
- surrounding material;
- expected wear;
- whether the mating feature should be replaceable.
For frequently operated equipment, a locating bushing can provide a defined and serviceable mating interface.
JW Winco, for example, specifies locating bushings as accessories for several indexing-plunger families.
Do not treat the receiving hole as an afterthought.
Pin and mating feature should be reviewed together.
8. Consider access and actuation
A positioning mechanism that is technically correct can still be inconvenient if the operator cannot reach it.
Check:
- pull direction;
- available hand clearance;
- surrounding machine frames or guards;
- mounting orientation;
- frequency of adjustment;
- whether the operator must hold the plunger while moving the mechanism.
For difficult-to-access locations, remote actuation may be possible in some indexing systems. KIPP, for example, offers Bowden-cable-operated indexing plungers specifically for inaccessible installation spaces or where remote operation is needed for ergonomic or safety reasons.
That does not mean every application needs remote actuation.
It illustrates a broader selection principle:
actuation method should be chosen from the installed machine environment, not just from the component dimensions.
9. Plan for repeated adjustment and wear
Positioning mechanisms that are adjusted frequently should be evaluated over repeated cycles.
Inspect the surfaces that actually make contact:
- plunger pin;
- mating hole;
- locating bushing;
- mounting thread or body;
- surrounding machine structure.
If the mating hole becomes the primary wear surface, replacing or repairing the machine component may be more difficult than replacing a dedicated bushing.
For frequently adjusted equipment, consider whether the interface can be designed so the expected wear components are accessible and replaceable.
This is especially relevant when maintaining the original positioning relationship matters over the service life of the machine.
10. Common machine-positioning problems
The machine element does not return to exactly the same setting
Determine whether the position is established by a positive locating feature or only by friction and visual adjustment.
If repeatable discrete positions are required, an indexing arrangement may be more appropriate.
The plunger repeatedly drops into holes during adjustment
If the mechanism needs to move freely across multiple indexed positions, review whether a lock-out version is appropriate.
The plunger can be disengaged accidentally
Where unintended retraction is a concern, review whether a safety or protected actuation design is required.
The pin is difficult to engage
Check alignment between the plunger and mating feature, hole condition, engagement geometry and mounting position before simply increasing clearance.
The indexing hole is wearing
Review operating frequency and consider whether a replaceable mating bushing would provide a more serviceable interface.
The operator cannot reach the plunger
Review the complete installed environment. A different actuation direction, mounting arrangement or remote operating mechanism may be more suitable.
11. What information should be included in an RFQ?
For locating and indexing components used in machine positioning, provide as much of the following information as possible:
- component type or existing part number;
- drawing or dimensional sketch;
- plunger or locating-pin diameter;
- thread or mounting method;
- required pin travel or engagement;
- mating hole or bushing dimensions;
- number and spacing of indexed positions;
- whether lock-out is required;
- whether protection against accidental disengagement is required;
- actuation and access requirements;
- operating or adjustment frequency;
- material requirement;
- quantity;
- existing component information for replacement applications.
If the component type is unknown, describe the movement instead:
What moves? Where must it stop? How often is it adjusted? Must the pin remain retracted? What happens after it engages?
Those answers often narrow the component choice more effectively than a generic product name.
12. Match the component to the positioning requirement
A practical starting point is:
Need a repeatable fixed reference?
Review Locating Pins & Bushings.
Need several predefined adjustable positions?
Review Indexing Plungers.
Need the plunger to remain disengaged during movement?
Review a Lock-Out Indexing Plunger.
Need to reduce the risk of unintended release?
Review an appropriate Safety-Lock / Protected Indexing Design, where the application requires it.
Need a replaceable mating interface?
Review a compatible Locating Bushing.
Need continuous rather than discrete adjustment?
An indexing plunger alone may not be the correct positioning method; review the complete adjustment and clamping mechanism.
Position the machine by function, not by component name
Machine positioning becomes easier to specify when the motion is defined first.
Ask:
Is the position fixed or adjustable?
Is adjustment continuous or indexed?
Should the pin automatically engage or remain retracted?
Could it be disengaged unintentionally?
What happens at the mating interface after repeated use?
Then select the locating, indexing and locking components that support that operating sequence.
If you are replacing an existing positioning component or designing a new adjustable machine element, send the drawing, existing part number or key dimensions for component review and quotation.
