SoftIntegration just released Ch Mechanism Toolkit 1.5.

Ch Mechanism Toolkit is based on C/C++ interpreter Ch.
With Ch user-friendly high-level numerical and graphical plotting
features, as well as easy to use QuickAnimation for animation of
mechanisms, Ch Mechanism Toolkit becomes a must-have toolkit
for mechanism design and analysis.

Ch Mechanism Toolkit contains many mechanism classes and objects for
design and analysis of commonly used mechanisms such as fourbar linkage,
five-bar linkage, six-bar linkage, crank-slider mechanism, and
cam-follower system.

Ch Mechanism Toolkit can be conveniently used for Web-based mechanism design
and analysis of many different mechanisms along with free Ch CGI Toolkit.

Ch Mechanism Toolkit comes with the source code and examples. It is available
in Windows, Mac OS X, Linux, HP-UX and Solaris.

More about Ch Mechanism toolkit can be found at