How to properly measure the final drive?

Our company specializes in the sale of final drives and travel gearboxes. Quite often, customers have problems with their correct dimensioning. Below we will show how to measure the final drive, hydromotor.

Hydromotor is a travel gearbox together with the travel motor. Our offer includes both planetary gears/final drives as well as complete hydromotors. To choose the right engine, you need some basic information. Of course, the VIN of the machine or the catalog number of the part are also useful. But to be 100% sure that the hydromotor purchased by us will fit, it’s best to measure it properly.

Mounting holes

When choosing a hydromotor or reduction gear, the seller will certainly ask for the number of mounting holes to the frame and the number of mounting holes to the drive sprocket. In Figure 1 we can see the location of these holes. The top two pictures show the holes for the frame, while the bottom pictures show the mounting holes for the drive sprocket. Very often the number of holes is correct, but their spacing may vary. That is why it is always worth measuring the distance between the holes. We will then be 100% sure that the given final drive/hydromotor will fit the machine. Of course, it is possible to remake the mounting holes, but this applies to troublesome, extreme situations.

To enter the number of holes, there is no need to remove the hydraulic motor from the excavator. The rack mounting bolts are easily visible from the drive star side. However, from the engine side, it is enough to remove the frame cover, clean it of sand and count the number of screws. The case is slightly different in the case of the diameter of the hole in the frame and the diameter of the hole in the drive sprocket.

Hole diameters

We need to pull out the hydromotor and carefully measure the diameters. We cannot give them “more or less” or approximately. The dimensions must be precise as individual models may vary by 5 or 10 millimeters. The diameters are best measured with a caliper – a tailor’s tape measure or a ruler will not work in this case. Diameter of the hole in the frame is measured from the travel motor side. And the diameter of the hole in the drive wheel “from the bottom”. In Figure 2 we can see exactly what dimensions are meant.

If we have a small hydromotor with a small diameter between 140 – 160 mm, there shouldn’t be  problems. However, if the hydromotor is larger, e.g. the diameter is over 300 mm, we may need a large, professional caliper. And probably help with measuring 😉

We hope you find this short article on how to measure final drive correctly will be of help. It’s not really difficult or time-consuming – it literally takes 1-2 minutes. However, it will help to avoid unnecessary mistakes.