High torque motors are practically simply a regular, internally commutated brushless DC Motors mounted with extra gear mechanism on top, to either boost the torque or to decrease the RPM (Revolutions per minute). These DC motors are noiseless powerful and can be utilized in several hobbyist and commercial application.
Reducing the RPM while maintaining high torque would require adding up more complex gear mechanism therefore the cost of these High torque DC motors mainly depends on the RPM, torque and quality of the motors.The engine shaft from the bottom electric motor though a transmission connects the tiny gear box fixed at its front portion, which in turn generates the required torque while keeping the RPM low, the whole gears and gear heads are doped with thick 
viscous grease lubricant.
These High torque Motors seriously different RPM’s such as, 5 RPM, 10 RPM, 100 RPM, 300 RPM, 1000 RPM and so on. The expense of these geared motors is founded on the RPM, usually lesser RPM costs a lot more than those of higher RPM.
Applications
High torque and low rpm DC motors are well suited for robotic and hobby applications, thought the size of the electric motor is a matter of concern since it is quiet large in size due to additional gear box but nonetheless it would save the trouble and cost of adding external gears to the assembly of robots where just the standard DC motors wouldn’t do well. The High Torque, Low RPM DC motors comes with inbuilt gearbox system providing necessary torque for your robotic software. Hence these motors would be the many favorable choice for the hobbyist robotic projects and tutorials Leaf Chain posted right here.