Complex sentence: These were of three incompatible types with different electrical equipment and engines, and to make a uniform fleet units were fitted with Westinghouse brakes and cars with different engines regeared to allow these to work in multiple with other cars.
Split into simpler sentences: These were of three incompatible types, with different electrical equipment and engines. In order to make a uniform fleet, units were fitted with Westinghouse brakes and cars with different engines were regeared to allow these to work in multiple with other cars.