Scissor lift that locks at a variable height

A scissor lift for raising and lowering a heavy object, comprising:

• an upper platform for supporting a heavy object, comprising guided rollers mounted on axles;
• a lower frame comprising guided rollers mounted on axles;
• a scissor lift mechanism fastened to the axles of said upper platform guided rollers and to the axles of said lower frame guided rollers, that raises and lowers said upper platform;
• a locking mechanism comprising protrusions protruding outward of said upper platform, each protrusion corresponding to a different height of said scissor lift mechanism, wherein at least one of the guided rollers within said upper platform comprises a spring-loaded pin for engagement in the protrusions, thereby locking said scissor lift mechanism into place at a height corresponding to the protrusion into which the spring-loaded pin is engaged;
• and
• a release mechanism that unlocks said scissor lift mechanism, comprising a shaft, outside of said upper platform, with capped pins that are bound within said protrusions and that move further into said protrusions, to disengage said spring-loaded pin from the protrusion into which said spring-loaded pin is engaged, when said shaft is pushed towards said upper platform.