How to Lock Out the Deck Height on a Bush Hog 2715L When the Cylinder Fails

[MikePhua]

When the hydraulic cylinder on a Bush Hog 2715L fails and bypasses oil, preventing deck lift, the lockout procedure becomes a mechanical challenge requiring improvisation and safe lifting techniques. Operators must manually raise the deck to align the lockout pin without relying on hydraulic pressure.
Bush Hog 2715L Overview
The Bush Hog 2715L is a heavy-duty flex-wing rotary cutter designed for agricultural and roadside mowing. With a cutting width of 15 feet and a recommended tractor PTO horsepower of 70–160, it’s built to handle thick brush, grass, and light saplings. Bush Hog, founded in Alabama in 1951, has produced millions of rotary cutters and remains a leading name in land maintenance equipment.
The 2715L features single-acting hydraulic cylinders for deck lift and wing fold, meaning hydraulic pressure is used to raise components while gravity lowers them. The deck height is typically controlled by a cylinder and lockout pin system, allowing the operator to set and hold the cutting height.
Terminology Notes

• Single-Acting Cylinder: A hydraulic cylinder that uses pressure to move in one direction, with return motion relying on gravity or external force.
  
• Bypassing Oil: A condition where internal seals fail, allowing hydraulic fluid to leak past the piston, reducing pressure and movement.
  
• Lockout Pin: A mechanical pin used to hold the deck at a fixed height when hydraulic lift is unavailable or during maintenance.
  
• Turnbuckles: Adjustable threaded rods used to fine-tune linkage length and alignment.
  

Symptoms and Diagnosis
In this case, the deck cylinder was bypassing so severely that it could not lift the deck at all. Hydraulic oil was visibly shooting out of the vent, confirming internal seal failure. The operator needed to remove the cylinder but couldn’t engage the lockout pin due to the deck’s low position.
Manual Lifting and Lockout Procedure

• Use a Bottle Jack or Beam Lift: Place a bottle jack under the deck at a reinforced point. If no solid lift point exists, use a beam or cribbing to distribute force and avoid bending the deck.
  
• Lift Incrementally: Raise the deck 2 inches at a time, repositioning supports as needed. Safety blocks or jack stands should be used to prevent collapse.
  
• Align Lockout Pin Mechanism: Once the deck reaches the correct height, adjust turnbuckles or linkage arms to align the lockout pin holes.
  
• Insert Lockout Pin: Secure the deck mechanically before removing the cylinder. Double-check alignment and stability before proceeding.
  

Alternative Techniques

• Use Terrain to Your Advantage: Drag the mower over a small hill or ditch to elevate the rear wheels and lift the deck naturally.
  
• Switch Hydraulic Valves: If the tractor has multiple auxiliary valves, try a different one to rule out valve failure.
  
• Inspect Hoses for Internal Collapse: A failed hose may act like a one-way valve, preventing cylinder actuation.
  

Field Anecdotes and Practical Insight
In Kansas, a farmer used an 18-inch beam salvaged from a barn floor to lift a forage harvester 2 inches at a time using a 3-point hitch. The same principle applies to the Bush Hog—slow, controlled lifting with stable supports can overcome hydraulic failure.
In Wisconsin, a technician discovered a failed hose that mimicked cylinder bypass. Replacing the hose restored function, saving the cost of a new cylinder.
Recommendations for Maintenance and Safety

• Replace Cylinder Seals Promptly: Bypassing oil indicates internal damage that will worsen over time.
  
• Keep Lockout Pins Lubricated and Accessible: Rusted or misaligned pins complicate emergency procedures.
  
• Use Reinforced Lift Points: Avoid lifting on thin sheet metal or unsupported deck edges.
  
• Document Hydraulic Failures: Track seal life and hose integrity to anticipate future issues.
  

Final Thoughts
When hydraulics fail, mechanical ingenuity becomes essential. The Bush Hog 2715L’s deck lockout system is designed for safety, but only works if the deck can be lifted into position. With careful lifting, alignment, and pin placement, operators can bypass hydraulic limitations and perform necessary repairs. In the field, resourcefulness is often the difference between downtime and a successful fix.