How to Measure Crankshaft Deflection

What is Crankshaft Deflection?

Crankshaft Deflection happens after some time, amid the repeated and constant utilization of the crankshaft.
It is a procedure that happens out of sight as the motor works and, however it can’t be seen without a detection instrument, it causes huge harm to the

Without correcting the movements in the crankshaft after some time, the machine will wear unevenly, cause undue weight on the supporting segments.
This will diminish the valuable lifetime of the motor, making it wear out rashly. This normally happening issue can be effectively corrected with little

imagesimages (1)
Image reference:

The Need to Measure Deflection:

Crankshaft comprises of crank-webs, crank pins and journals along its length. The weight of the crankshaft is upheld by the main bearings at the journals.
Over some time frame as the motor continues running, the wear in the bearings may not be uniform across the whole length of the crankshaft.

This implies the crankshaft won’t stay in the underlying straight line yet will get bend either upward or downwards to a slight degree which may not be
noticeable with the exposed eye but rather could be adequate to cause hazardous levels of fatigue in the crank-webs. Which is why there is need of
measuring crankshaft deflections at regular intervals to guarantee that the alignment of the shaft is within secure and permitted limits.

How to take Crankshaft Deflections?

The figure below gives an idea of which measurement is taken to discover the deflection of the crankshaft. As should be obvious from the image a dial
gauge is placed between the crank-webs to discover the distance between them. If the deflection is measured after a specific time interval, it is
must that it should be taken at the exact same point otherwise the reading won’t give a genuine reflection about the level of deflection.
Typically a center punch is utilized to make markings with the goal that each time the deflection is taken at a similar point.


Aside from using the exact same point on the crank-webs for measuring deflection there are different factors which should be remembered and these
incorporate load on the motor, trim, hog, sag etc. Preferably the deflection should be taken at four points of the crank namely top, bottom and the
two sides.

In genuine practice anyway the bottom reading isn’t taken because of risks of fouling by the connecting rod and rather readings are taken on both sides
of the bottom position, and in total 5 readings are taken from each crank-web at the positions appeared in the figure below.

5 positions (1)
Image reference:


Wireless Laser Rangefinder

Motionics Wireless Laser Rangefinder (WLRF) packs a WASP-200 LRF ultra-compact laser rangefinder. It is capable of quickly and accurately identifying the distance to a target up to 200m away. With built-in Bluetooth Low Energy transmitter, laser measurement readings can be wirelessly viewed and collected on iPhone/iPad.

There is an inclinometer embedded inside WLRF to monitor device tilt angle simultaneously with laser distance measurement, facilitating applications that require intersection scanning.

WLRF has a standard ¼-20 thread mounting hole to allow user to easily mount the device on a common tripod for quick and steady setup.



  • Dimension: 120 x 78 x 43 mm
  • Weight: 300 g
  • Resolution: 1 cm
  • Accuracy: 10 cm
  • Measurement Range: 0.2 to 125 m (18% reflectivity); 0.2 to 200 m (80% reflectivity)
  • Laser Class: Class 1
  • Wireless Data Rate: 10 Hz
  • Transmission Range: up to 10 m
  • Working Temperature: 0 – 50ºC
  • Battery: 3200 mAh rechargeable
  • Battery life: 30 hrs

Check out our store for more information: 

More information:

MultiGage Reader App

Using our WiMER and BlueDial to wirelessly collect readings make displacement measurement simple. Yet it can be even more effective with the help of MultiGage Reader app.

MultiGage Reader app is able to connect up to 14 WiMER or BlueDial and receive readings from all of them at the same time. Each device will be assigned with an individual panel to display measurement reading, max, min, TIR and average value. User can disconnect a device or add more devices without interference in other devices and measurement undergoing. It is an ideal tool for simultaneous measurement at different locations along a long pipe or a shaft.

MultiGage Reader provides 2 options for data recording: continuous recording at up to 10 samples/sec or one by one capturing with button tapping. Recorded data can be plotted in a user interaction enabled graph (zoom, pan, screenshot) or exported in CSV file via email for further assessment.

To better visualize sensor readings, we embed a probe meter for both individual device (activated by tapping the sensor reading) and a group of devices (activated through more button). Two different options of probe meters with different numbers of ticks are available for different resolution requirements. Additional, users can freely set the range of the probe meter to further adjust display resolution. An analog needle rotates while sensor reading changes. Two limit handles indicate max and min values the device has reached.

For those who don’t have our hardware devices, the simulation mode will demonstrate major functioinalities of this App.

Available at the Apple App store:

Help videos’ playlist for the MultiGage Reader App:



No more hassle of cables and connectors, BlueDial is the new solution for wireless measurement of displacement.

BlueDial integrates Mitutoyo digimatic dial indicator with Bluetooth Low Energy technology for users to directly view and record measurement readings on smart devices and PCs.





Motionics WiMER Series 1

WiMER-1 is a wireless measurement device connecting to digital instruments. It reads Mitutoyo digital micrometer/dial/caliper readings and communicates wirelessly with iPhone/iPad via Bluetooth Low Energy, allowing user to view real-time plot directly on the screen of iPhone/iPad.

And now with the help of USB Bluetooth Dongle and our FREE software, WiMER can also wirelessly send instrument readings to any Windows PC.

• Dimension: 2.50 x 1.63 x 0.80 in
• Resolution: 0.001 mm (depending on the instrument)
• Range: 12.7 mm (depending on the instrument)
• Sampling Frequency: 5/10 Hz
• Wireless Working Range: up to 10 m
• Working Temperature: 0-50 ºC
• Battery: 400 mAh rechargeable
• Charging: 5 VDC USB and 110VAC


Have any questions?