English to Russian Tech/Engineering Construction / Civil Engineering экскаваторы

Breakout force, basically, is the ability of an excavator to "break-out" difficult material from the ground or excavation "face".
What is breakout force? It's the force generated at the tip of a bucket as it rotates into the material. According to the estimated position where the digging force is exerted, there are two components.
The first of these, Maximum radial tooth force due to the bucket cylinder - or bucket digging force - which you see illustrated in the animation, is generated by the bucket cylinder as it moves through the specific geometry of its linkage. To maximize Breakout Force, the Alfa (arm cylinder and ***arm Structure jointed angle***) & the beta (Bucket cylinder and yoke jointed angle) should be close to 90 degree. The Length of A & C should be as large as possible, and the length of D & B should be as small as possible.

Хоть убейте, не пойму что угол. Между гидроцилиндром рукояти и самой сочлененной рукоятью???

Спасибо!