Understand the linkage before measuring a replacement
This guide explains the mechanism and the interfaces to identify. For a dimensioned enquiry, use the separate linkage measurement guide and submit photographs or a drawing of the installation.
What Is a Wiper Linkage?
A wiper linkage is the mechanical assembly that carries motion from the wiper motor to the wiper arm pivots. In many conventional wiper systems, the geared motor drives a crank mechanism that converts continuous rotation into an oscillating motion at the wiper pivots. Other drive configurations may use different control arrangements. The linkage sits between motor and arms, and on a commercial vehicle it largely determines how far, how fast and in what pattern the blades travel across the glass.
A linkage is not a single part but a matched set — crank, one or more rods, ball joints, pivots, bushings and a mounting bracket — built to a fixed geometry. Pivot spacing, rod length and crank offset are calculated from the windshield area and required sweep, so assemblies are not interchangeable between models even when they look alike.
Main Components of a Wiper Linkage Assembly
Each part has one job and each wears in its own way. The table follows the path the motor’s movement takes.
| Component | Function in the assembly | Typical wear point |
|---|---|---|
| Crank arm | Clamps to the motor output shaft and turns with it, converting shaft rotation into a circular path | Splines, retaining nut, crank offset |
| Connecting rod (drive rod) | Carries the crank’s circular motion to the first pivot and sets the stroke length | Ball sockets at both ends |
| Driven rod (secondary rod) | Couples the two pivots in a dual-arm system so both arms sweep together | Socket play, phase alignment |
| Ball joint and socket | Lets the rod change angle as it swings, without a fixed hinge | Boot damage, corrosion, free play |
| Pivot shaft and housing | Defines the arm’s rotation axis and carries the arm’s load | Shaft play, seal, housing cracks |
| Bushings | Provide the low-friction bearing surface inside joints and pivots | Lost motion, squeak |
| Mounting bracket | Holds the assembly to the body at the designed position | Distortion, loose fasteners |
Terminology differs between suppliers — drive rod, main rod, link rod and transmission linkage all name the same part. What identifies a component is its position in the chain, not its label. The arm is separate; see our wiper arm manufacturer page for mounting and length conventions.
How Does a Wiper Linkage Work?
- Motor output rotation. In a conventional arrangement the gearbox turns its output shaft slowly and with high torque, and the crank converts that continuous rotation into oscillation.
- Crank motion. The crank arm is fixed to that shaft, so the rod’s attachment point travels a circle whose radius is the crank offset.
- Connecting rod movement. The rod is a rigid link jointed at each end. As one end circles, the other is pushed and pulled along the rod’s axis.
- Pivot rotation. The pivot turns that push-pull into rotation about a fixed axis. The lever length between shaft and rod attachment sets how many degrees it turns per stroke.
- Wiper arm sweep. The arm clamps onto the pivot shaft, so shaft rotation is arm rotation, and the blade traces an arc across the glass.
Three dimensions decide the result: crank offset sets the stroke, rod length sets the phase, pivot spacing sets the swept area. Change any one and the blades miss part of the glass or travel past its edge.
In many mechanically linked dual-arm systems, one pivot receives motion through the main linkage and the second pivot is coordinated through an additional connecting rod. The exact arrangement depends on the system design. How the two arms move relative to each other is set by the linkage geometry and the drive structure, not by a single universal pattern. Where the arms are coupled through the linkage, refitting one arm one spline out changes that relationship, and the blades can then collide even though every part is correct.
The motor side has its own selection logic; our windshield wiper motor guide covers output rating, wiring and park control.
What Are the Main Functions of a Wiper Linkage?
The linkage does more than pass movement along; five functions matter when specifying or replacing one.
Motion transmission. It delivers torque from the motor to arms mounted elsewhere, which is why the motor can sit low in the cowl, protected from water and debris.
Motion conversion. Continuous rotation becomes reciprocating oscillation; a rotating shaft alone could not drive a blade that must reverse at each end of its stroke.
Coordination between arms. Where two arms are coupled through the linkage, their relative motion is set by the linkage geometry and drive structure, so the arms move as a coordinated pair rather than independently.
Sweep geometry. Crank offset, rod length and pivot position define the swept area, park angle and clearance to the A-pillar. Coverage is a linkage property, not a blade property.
Mechanical support. Pivots and bracket carry the arm’s load and react to blade pressure, wind and ice. A distorted bracket changes the arm angle even when the linkage is sound.
The linkage does not return the blades to park by itself: the park switch or position electronics in the motor stop the shaft at a defined angle, and correct crank indexing turns that angle into the right arm position.
Wiper Linkage Types and Vehicle Applications
Linkage designs are described along several different axes. Supplier catalogues do not always separate them, which is why the terms are easy to mix.
Number of arms. Single-arm systems drive one blade, usually on small rear or side glass. Dual-arm systems drive two and are the norm for windshields.
Arm motion. Two common patterns are a tandem layout, in which both arms sweep in the same direction, and an opposed layout, in which they sweep toward each other and park at opposite ends. Terminology varies between suppliers: "parallel" is sometimes used for the same-direction pattern, and "vertical" for a park position in the opposed pattern. Where the two swept areas cross near the centre, the layout is often described as overlapping.
Pivot arrangement. Pivot spacing and pivot position relative to the cowl determine how much of the glass each arm covers. Two systems can share the same arm motion and still differ in pivot spacing.
Drive structure. A linkage may be driven by a single crank with a main rod and one or more secondary rods, or by a symmetrical arrangement in which the rods cross. This affects load sharing and how much space the assembly needs behind the cowl.
Product examples in these arrangements: NLG-003 overlapped linkage and NLG-006 vertical linkage.
Application follows from those choices. Coaches and city buses use long rods, wide pivot spacing and heavier pivots because the glass is large and the blades long. Trucks tend to use shorter arrangements with the motor close to the linkage. Off-highway equipment often parks the blades vertically and relies on heavier plating against dust and washdown.
Product naming on this site. The product categories and product names used on this website include overlapped, ordered and vertical, with cross and interlocking used within the same product naming. These are LEILI’s own product categories and product naming; they are not presented here as an industry-wide classification standard, and they should not be read as a strict one-to-one mapping onto the categories above. Confirm the arrangement on the drawing or against the original part rather than from the name alone.
Basic Inspection and Maintenance Considerations
Most linkage problems are visible before they become failures. With the ignition off and blades at rest, look under the cowl for a rod off its socket, cracked bushings, or rust at the joints. Then rock each rod: slight rotational play is normal, but up-and-down movement at a socket means wear.
Two maintenance practices may help reduce avoidable wear and damage. Keep the area clear of leaves and grit, which can act as an abrasive paste inside the joints, and avoid running the wipers on dry glass or over ice, which can load the rods and pivots beyond their normal working range.
Do not lubricate sealed or maintenance-free joints unless the manufacturer specifies it; the wrong lubricant can soften the bushing. Serviceable joints follow the vehicle or linkage manufacturer’s schedule.
These are condition checks only. If the complaint is a symptom — blades stopping in the wrong place, one arm moving and the other not, or a motor that runs without moving the arms — work through the windshield wiper troubleshooting guide, which maps symptoms to causes.
How to Identify the Correct Wiper Linkage
A linkage is matched to the vehicle, so identification is a specification exercise, not a visual one. Collect these before enquiring:
- OE part number, plus vehicle or equipment model, year and variant.
- Pivot spacing, measured centre to centre between the two pivot shafts.
- Mounting arrangement — bracket hole pattern, orientation and distance to the bulkhead.
- Rod and crank dimensions, or the original part for comparison.
- Sweep requirements — sweep angle, park side, and whether the blades overlap at the centre.
- Motor interface — output shaft type and crank mounting.
Photographs of the assembly in place, taken with a scale, resolve most ambiguities. Our guide on how to measure wiper linkage dimensions walks through the measurement points, and the bus brand matching matrix confirms the application first.
Where a like-for-like replacement is unavailable, assemblies can be built to agreed specifications. As a commercial vehicle wiper linkage manufacturer, LEILI matches pivot spacing, rod length and crank geometry to the original installation.
Frequently Asked Questions
What is a windshield wiper linkage?
The assembly of rods, joints and pivots connecting the wiper motor to the wiper arms. It transfers the motor’s rotation and sets the path the arms sweep.
What does a wiper linkage do?
It converts continuous motor rotation into reciprocating arm movement, coordinates the movement of the two arms where both are linked, and defines the swept area and park position.
Is a wiper linkage the same as a wiper motor?
No. The motor produces rotation and contains the park switch; the linkage transmits and converts it. If the motor runs but the wiper arms remain stationary, a disconnected or damaged linkage is one possible cause. The motor output connection and related components should also be inspected.
How does a wiper linkage move two wiper arms?
In many dual-arm systems one pivot is driven by the main rod from the crank and a secondary rod coordinates the second pivot. How the two arms move relative to each other depends on the linkage geometry and the drive structure, so the relationship is not the same on every system.
Are all wiper linkage assemblies interchangeable?
No. Pivot spacing, rod length, crank offset, mounting pattern and sweep angle are vehicle-specific. Assemblies that look alike can differ enough to change the swept area or make the blades collide.
