Motor shield supplies less power to the gear motor

Other Hardware Motors, Mechanics, Power and CNC
1

I was trying to build to car robot but failed to do that as when i supply power(6 V) to the motor shield it supplies so less power to the motor shield that the motor gear(i uesd gear motor where 6 V was recommended to work) does not move.I made a very simple connections .I have just used arduino uno to write simple code to run. The servo works fine but the motor gear does not work.When i use LED light then it works as LED requires less power to work.Please, help me.

Thanks in advance.

2

What motor shield. One with L239D chips?
If so, those ancient chips drop a lot of voltage in h-bridge mode.
About 2.6volt is lost @ 600mA motor current.
You motor might only get 3.4volt on a 6volt supply, assuming the batteries are holding up at that current.
Try a 9volt supply (AA batteries) for a 6volt motor, or use more modern mosfet based h-bridge chips.
Leo..