Resin gear device with resin lubricating grease composition

An actuator comprising:

• a motor;
• a multi-stage gear device, including a first stage gear attached to a rotation shaft of the motor, wherein a gear of each stage engages with a gear of a next stage;
• and
• a base member on which the multi-stage gear device and the motor are mounted,
• wherein a grease composition for resin is applied to an engaging part between the gears, and the grease composition for resin includes:
• (a) a base oil including a poly-alpha-olefin oil with a kinematic viscosity at 100° C. of 4 to 6 mm2/s;
• (b) a thickening agent which is lithium soap;
• (c) a viscosity increasing agent;
• (d) a solid lubricant;
• and
• (e) an anti-wear agent, and
• wherein the NLGI (National Lubricating Grease institute) consistency number of the composition is 00, 0, 1, or 2.

A gear device at least comprising:

• a first stage gear attached to a rotation shaft of a motor;
• and
• a second stage gear engaging with the first stage gear;
• wherein at least one of the first stage gear and the second stage gear is resin-made, and a grease composition is applied to at least an engaging part between the first stage gear and the second stage gear, and
• wherein the grease composition includes:
• (a) a base oil including a poly-alpha-olefin oil with a kinematic viscosity at 100° C. of 4 to 6 mm2/s;
• (b) a thickening agent which is lithium soap;
• (c) a viscosity increasing agent;
• (d) a solid lubricant;
• and
• (e) an anti-wear agent, and
• wherein the NLGI (National Lubricating Grease Institute) consistency number of the composition is 00, 0, 1, or 2.