In this tutorial, you’ll build a latch model that is required to securely clamp two halves of large shipping containers together. The latch design problem is based on a latch developed by Earl V. Holman of North American Aviation, Inc., Downey, CA, under contract to the Manned Spacecraft Center in Houston. This latch is one of twelve used to clamp the Lunar Excursion Module to the Command and Service Module in the Apollo program.
Figure 2 Physical Model of Hand Latch Design
Figure 3 shows a virtual model of the latch. The latch is clamped by pushing down on the operating handle at POINT_4. This causes the pivot to rotate around POINT_1 in a clockwise direction, drawing back POINT_2 of the hook. As this happens, POINT_8 of the slider is forced downward. Finally, as POINT_8 passes through the line between POINT_9 and POINT_3, the clamping force reaches its maximum. POINT_8 should move below the line created by POINT_3 and POINT_9, followed by the operating handle coming to rest on the top of the hook. This sets the latch near the maximum force point, but allows a reasonable release force to open the latch.
Figure 3 Adams/View Latch Model
Based on the description of the latch operation, the relative layout of POINT_1 through POINT_9 is important in ensuring that the latch will meet the design requirements. Therefore, when your latch model is assembled and tested, you will want to change the relative locations of the points to see their effect on the design requirements.