Question

37. Which of the following represents proper knife registration

• A. Mid-point of the stroke is centered between adjacent guards.
• B. Outer end of cutter bar is ahead of inner end.
• C. The knife is in line with pitman.
• D. Both the ends of cutter bar are at same level.

Hint:

Registration = Knife sections centering on the guards at each end of the stroke (or centering between guards at mid-stroke).
Lead = Outer end of the cutter bar set forward (offsets draft force).
Alignment = Keeping the knife in line with the pitman.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
In a cutter-bar mower, the cutting mechanism consists of a reciprocating knife assembly sliding inside stationary protective guards.
To achieve clean, clog-free cutting of crops, the knife sections must be properly aligned with the guards during their reciprocating movement, which is referred to as registration.

Step 2: Detailed Explanation:
Let us analyze the geometric parameters of a cutter bar mower:
- Knife Registration: A mower knife is in proper registration when the center of each individual knife section aligns exactly with the center of the corresponding guard at the extreme end of each stroke.
Since the total stroke length of the pitman drive is designed to be equal to the spacing between adjacent guards (typically \(76.2\text{ mm}\) or \(3\text{ inches}\)), the knife section travels from the center of one guard to the center of the next.
Consequently, at the exact mid-point of the stroke, the knife section must be positioned precisely midway (centered) between the two adjacent guards.
If the knife is out of registration, the sections will not travel fully or will overshoot the guards, causing uncut patches of grass and clogging the mower.
Thus, Option (A) represents proper knife registration.
Let us evaluate the other options for clarity:
- Option (B) describes "Cutter Bar Lead", where the outer end of the cutter bar is set slightly ahead of the inner end to offset the rearward deflection caused by crop resistance during forward travel.
- Option (C) describes "Cutter Bar Alignment", ensuring that the reciprocating knife, the pitman rod, and the drive flywheel form a straight, co-planar line to minimize wear on the joints.

Step 3: Final Answer:
Proper knife registration is represented when the mid-point of the stroke is centered between adjacent guards.