Here are some ideas to motivate your workers:
Taylor told that you can raise the productivity when you pay your workers per piece rate.
It is also good to let your workers know that they are a part of your company. Show this with special trainings.
Mayo told that peaople work harder when they think they are more important.
Herzberg told that money is not for motivation because when somebody know´s that he get his money he is not motivated to work. So it is better when you praise them.