Adjusting the Kiddy Crawl Speed on Excavators: Left and Right Lever Calibration

[MikePhua]

When operating heavy machinery such as an excavator, precise control over the movement and speed of the machine is essential. This is particularly true for functions like the "kiddy crawl" or slow-speed drive, which allows for fine, controlled movements during tasks that require high precision, such as grading, trenching, or maneuvering in tight spaces. One common issue that operators face is when the speed of the left and right levers (or tracks) is inconsistent. This can significantly affect the machine's performance and operator efficiency.
This article will explore the problem of unequal speed between the left and right levers, often referred to as the "kiddy crawl" speed issue, as well as how to adjust the levers to ensure smooth and balanced operation.
Understanding the "Kiddy Crawl" Speed Function
The "kiddy crawl" refers to a low-speed operation of an excavator, often engaged for precision work. This mode allows the operator to move the machine at a very slow pace while maintaining full control over its movements. It’s typically used for tasks like:

• Grading or finishing work
  
• Digging around delicate structures or utilities
  
• Tight space maneuvering
  

In this mode, the levers for forward and backward movement are sensitive, allowing for small, controlled adjustments in direction and speed. The issue arises when the speed of the left and right tracks or wheels becomes uneven, causing the machine to move or behave erratically, which can lead to inefficiency or even damage.
Common Causes of Uneven Crawl Speed
The most common causes of uneven "kiddy crawl" speed are linked to the mechanical or hydraulic systems of the excavator. Below are some factors that can contribute to this problem:

1. Misalignment of Control Levers
   • Over time, the control levers can shift slightly out of alignment. This results in unequal hydraulic pressure being applied to the left and right tracks. When the levers are not calibrated properly, one track may move faster than the other, leading to uneven movement.
     
2. Hydraulic System Issues
   • Hydraulic pressure is crucial for controlling the tracks. Uneven pressure or blockages in the hydraulic lines can result in slower movement of one track compared to the other. This can be caused by dirt or debris in the hydraulic fluid or worn-out hydraulic components, such as pumps or motors.
     
3. Differential Wear on Tracks or Drive Components
   • If one track has suffered more wear than the other, it may not engage or disengage as effectively. This results in the two sides not operating at the same speed. Common signs of this include uneven tread wear or damaged drive gears.
     
4. Control Valve Problems
   • The valves that regulate the flow of hydraulic fluid to each track could also be out of calibration. This can lead to one side receiving more or less fluid, affecting the overall speed of that track.
     
5. Faulty Sensors
   • Many modern excavators have sensors that help monitor and control the movement of the tracks. A faulty sensor can send inaccurate readings to the machine’s controller, causing one track to move faster than the other.
     

How to Adjust the Left and Right Lever Speed
Correcting the issue of uneven crawl speed requires addressing the root cause. Here are the steps to troubleshoot and adjust the left and right lever speeds:
1. Inspect Control Lever Calibration

• Start by checking the control levers for proper calibration. Ensure both levers are in the neutral position and aligned correctly. If the levers are physically misaligned, they may need to be adjusted to their correct position. This is often a simple mechanical adjustment.
  

2. Check Hydraulic Fluid and Pressure

• Inspect the hydraulic system for any leaks, blockages, or signs of contamination. Low or dirty hydraulic fluid can cause uneven pressure, affecting the performance of the tracks. Replace any worn or damaged hydraulic components such as hoses, pumps, or motors. Use the manufacturer’s recommended fluid type and ensure the fluid is at the proper level.
  

3. Clean or Replace Filters

• Dirty or clogged filters can restrict the flow of hydraulic fluid, leading to imbalanced pressure on the tracks. Cleaning or replacing the filters in the hydraulic system can help restore balance to the movement of the tracks.
  

4. Adjust the Hydraulic Valves

• If the issue is linked to hydraulic flow or pressure, it may be necessary to recalibrate or adjust the hydraulic valves. These valves control the amount of fluid being sent to each track. A professional technician will be able to perform this task and ensure the system is operating correctly.
  

5. Examine Track Condition

• Check the tracks for wear and tear. Uneven tread wear or damaged drive components can affect the performance of the tracks. If one track has excessive wear, consider replacing the track or components like drive sprockets or tensioners to restore proper function.
  

6. Test and Calibrate the Sensors

• If the excavator uses sensors to monitor track performance, inspect these sensors for faults. Clean or replace any faulty sensors, ensuring they provide accurate readings to the control system. Recalibrate the sensors if necessary to ensure the machine maintains balanced speed.
  

7. Perform a Full System Diagnostic

• For machines with advanced control systems, it’s a good idea to perform a full diagnostic test using the manufacturer’s diagnostic tools. This will identify any underlying issues with the machine’s electronics or sensors that might be contributing to the uneven crawl speed.
  

Preventive Maintenance Tips
To avoid encountering the "kiddy crawl" speed issue in the future, regular maintenance is essential. Here are some preventive tips:

• Regular Fluid Checks: Ensure the hydraulic fluid is changed at regular intervals, and always check the levels and quality of the fluid before use.
  
• Lubrication: Properly lubricate moving parts, including the levers, tracks, and drive components, to prevent wear and ensure smooth operation.
  
• Track Inspections: Inspect the tracks for wear and tear regularly, especially after extensive use. Look for signs of misalignment, loose bolts, or damaged components.
  
• Annual Calibrations: Have the machine’s hydraulic system and control levers calibrated annually or as per the manufacturer’s guidelines.
  

Conclusion
An uneven "kiddy crawl" speed on an excavator can significantly affect its performance, especially during precision work. By understanding the root causes and following a systematic troubleshooting approach, operators can restore balance to the machine’s movement and ensure smooth operation. Regular maintenance, timely adjustments, and proper care of the hydraulic system, control levers, and tracks are essential to avoid this problem and maximize the machine's lifespan and efficiency.