Spur Gearheads Huayan Tech offers compact and low noise SG series spur gearheads which can provide up to 3.8NM torque and 120000:1 gear ratio. Output shaft, gear material, bearing and gear ratio can be customized. SG1000 SG1020 SG1060 SG1080 SG1100 SG1000 SG1000 Series gearheads. SG1020 SG1020 series gearheads. SG1060 SG1060 series gearheads. SG1080 SG1080 series gearheads. SG1100 SG1100 series gearheads.