I am working currently on an optimized drive kit. The basic idea is to go for a direct drive based on my experience that I am running always in the 3rd gear. As on of first action I contacted a specialized company to scan an existing gear-box-housing (company name: modernes-engineering.ch)
The first scan created raw data in the are of 260 MByte (*.stl-file) with an accuracy of 0.02mm. The data was then reworked into a parametric model with a reasonable size of 4 MByte (*.stp-file). Such a small file can easily be handled in every CAD tool.
Why a direct drive?
There are different reasons:
- There is no need for changing gears since an electric motor provides the max. torque from zero speed. Hence the gear changing mechanism and its pinions can be removed.
- A direct drive (only differential) has less parts. Less parts means less noise, less weight, nearly no backlash and higher efficiency.
- My current drive needs an oil pump to supply the input pinion with gear oil. Without the input pinion I can get rid of the oil pump.
The next steps will be to start defining the different parts to fix the electric motor on top of the gear-box and to couple it with the main axle driving the differential.
I will keep you posted about the upcoming design steps.