Expanding force electric linear actuator

A belt driven linear actuator comprising:

• a support structure;
• an output shaft;
• a pulley system comprising:
• a plurality of fixed sheaves arranged to at least partially encircle the output shaft;
• a plurality of traveling sheaves coupled to the output shaft, the output shaft configured to pass through fixed sheaves and translate along an axis of travel, wherein the plurality of traveling sheaves are arranged such that a geometric average of belt tension created by spans of belt between the plurality of traveling sheaves and the plurality of fixed sheaves is located within the output shaft;
• and
• a belt extending between and around the plurality of fixed sheaves;
• and
• a belt drive mechanism configured to withdraw belt from the pulley system and pay out belt to the pulley system.

A method of operating a linear actuator, the method comprising:

• removing a portion of belt from a pulley system using a belt drive mechanism, wherein the pulley system comprises:
• a plurality of fixed sheaves arranged in to at least partially encircle an output shaft;
• a plurality of traveling sheaves coupled to an output shaft, the output shaft configured to pass through the fixed sheaves and translate along an axis of travel, wherein the plurality of traveling sheaves are arranged such that a geometric average of belt tension created by spans of belt between the plurality of traveling sheaves and the plurality of fixed sheaves is located within the output shaft;
• and
• the belt extending between and around the plurality of fixed sheaves and the plurality of traveling sheaves.