Stam , RG Le Tourneau developed wheel motors and dc type steer systems back in the 40s and 50s. What you will notice is the loaders still use hydraulic to operate the buckets. If it was practical LE Tourneau would have done it by now. They use battery power to assist the drive train up hill and recharge them on the way down into the open pit mines. Screw jacks are not as fast as hydraulic systems and are much more prone to wear and tear. Thank you for your reply. Lets just face it. Exhalt needs a fishing license.