Push or Pull When Climbing a Slippery Slope with an Excavator

[MikePhua]

The Physics Behind Excavator Movement on Slopes
Operating an excavator on steep, loose, or slippery terrain demands a deep understanding of hydraulic mechanics, weight distribution, and traction dynamics. The central debate among operators is whether to push or pull the machine uphill using the boom and bucket. Each method has its merits, but the choice depends on slope angle, soil composition, machine configuration, and operator experience.
Hydraulic cylinders generate more force when extending rather than retracting. This means that pulling—where the boom and stick extend to draw the machine forward—often provides more raw power than pushing. The reason lies in surface area: when extending, hydraulic fluid acts on the full piston face, whereas retracting reduces effective area due to the rod occupying space inside the cylinder.
Pulling Uphill Advantages
Pulling is generally preferred for several reasons:

• Greater hydraulic force due to cylinder extension
  
• Improved visibility of the slope and destination
  
• Anchor point above the machine, which stabilizes movement and reduces rollover risk
  
• Bucket acts as a brake when embedded into the slope during repositioning
  

Operators often keep the bucket planted in the slope while tracking forward, using a combination of boom extension and track movement. This dual action maintains traction and control, especially in muddy or log-covered terrain.
In one example, a crew working on a ship’s log deck in Victoria faced steep, slippery climbs multiple times per shift. They found that pulling with the boom low and bucket engaged provided the best stability, even when the logs were wet or green.
Pushing Uphill Considerations
Pushing can be effective in specific scenarios:

• Short, steep climbs where the bucket can be used to catch the machine if it slips
  
• Loose material where the bucket can dig in and create a temporary anchor
  
• Machines with limited boom-up tracking capability, such as older models with hydraulic limitations
  

However, pushing uphill with the bucket downhill carries rollover risks. If the machine slides and the bucket catches abruptly, it can pivot the excavator sideways, especially on steep grades. This is particularly dangerous if the counterweight swings downhill and destabilizes the center of gravity.
Drive Sprocket Position and Track Engagement
Another critical factor is the location of the drive sprockets. On most excavators, the sprockets are at the rear. When climbing, having the sprockets downhill ensures that the drive teeth engage the track directly, improving traction. If the sprockets are uphill, the machine may struggle to pull the track over the top rollers, reducing grip and increasing slippage.
Operators should also avoid lifting the tracks off the slope with aggressive boom movements. Maintaining full track contact maximizes friction and prevents the machine from digging holes or losing momentum.
Safety and Technique Tips
To climb safely:

• Move slowly and smoothly to avoid upsetting balance
  
• Keep the boom low and bucket engaged with the slope
  
• Reposition the boom and bucket incrementally to avoid sudden shifts
  
• Avoid booming up too high on steep slopes, which can shift weight backward
  
• Practice on moderate slopes before attempting extreme terrain
  

One operator in Pennsylvania recalled climbing a 200-foot slope steeper than 2:1 using an early Cat 235. The machine couldn’t boom up while tracking, so he had to push in short bursts, reposition, and sometimes clear rocks by hand. It took hours, but careful technique prevented a rollover.
Conclusion
Whether to push or pull an excavator up a slippery slope depends on machine design, terrain, and operator skill. Pulling offers more hydraulic power and stability, especially when the bucket serves as an anchor above the machine. Pushing can be useful in specific cases but carries greater risk. Understanding the physics and practicing controlled movements are key to mastering slope navigation in heavy equipment.