Final drive – how to measure it?

06.03.2023

Although off-the-shelf travel motors generally have the appropriate labels to match a particular excavator model, it is best to measure the final drive you use and give the parameters to your dealer. This way, you will be sure that the final drive you buy will be an ideal match. Unfortunately, clients often have problems with measuring their final drives correctly – that’s why we present you with this short guide on how to measure a travel motor.

Why is measuring final drives essential?

Selecting the correct travel motor (a complete final drive with hydro motor) requires a lot of precision – even just a few millimetres may affect the device’s work or even cause serious damages. Our company specializes in selling complete travel motors for tracked excavators – with our experts’ help, you will easily find a final drive that won’t differ from the original. All we need is some info.

What information should be given to the retailer?

The basic information is, of course, the serial number of your machine. To be sure you pick the right device, you should also give:

  • Inner and outer diameters of the travel motor (see fig. 1);
  • The number of hoses by the hydro motor;
  • The number of screw holes for fixing the hydro motor in the machine frame and pitch diameter (measurement B);
  • The inner diameter of the main opening in the machine frame (measurement C);
  • The number of holes for the drive wheel fixing bolts and pitch diameter (measurement E);
  • The inner diameter of the drive wheel (measurement D).

Besides this essential information, it’s also helpful to check the gear tooth count/size.

Fixing holes – how to measure them effectively?

Measuring holes in the machine frame is easy when the travel motor is disassembled. To accomplish this, you should open the hydro motor’s cover, disconnect the hydraulic hoses, and undo the screws. The spacing between screws in the machine frame may vary. If the spacing is even, simply say, how many holes are there. When the spacing is uneven, make a perpendicular photo that shows all holes and inform the seller about it.
After disassembling the travel motor, taking the B and C measurements is practically effortless – all you need is a simple measuring tape. You should also measure the fixing holes and give that info to the seller.

Measuring the travel motor

You should notice that figure 1 and additional figures 2 and 3 show the same measurements B, C and D, E. The only difference is in the method of measurement.

It’s way easier and more precise to take these measures when the travel motor and drive star are disassembled.

Fig. 2 shows how easily (with a simple measuring tape) you can take measures B and C.

Analogously, fig. 3 shows the same for D and E.

Measurement A, shown on fig. 1, is also easier to get when the travel motor is disassembled.

When the travel motor is mounted on the machine, you would have to use a big calliper to get these measurements.

To get measurements B and C, you should take off the hydro motor cover, on the inner side of the track.

D and E should be measured from outside.

If you don’t own a big calliper, you can take the final drive cover’s outer diameter, measurement F. It’s a supporting measurement, which will lower the risk of choosing the wrong final drive.

It is also important to specify the number of screw holes for attaching the hydro motor to the machine frame and the drive star screws.

Measuring final drives – summary

To be completely certain you get the right product when buying a travel motor, it’s a good idea to check the measurements of your final drive and give the values to the seller. Thanks to this, you will be sure that both the inner and outer diameters of the final drive will match your excavator. The measuring process doesn’t take long and with this guide, you can do it without issues.

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