Excavators provide an ideal platform for working on slopes when they are properly equipped and run by skilled operators. But this type of work requires a greater attention to detail than working on flat ground.
Excavators are capable of climbing some pretty steep slopes, but it takes extra care from the operators. They need to carefully assess the jobsite and the work to be performed.
Operators are ultimately responsible for their safety, the safety of the machine and the safety of surrounding equipment and crew members. But there is really no way to foresee all of the things that can go wrong while working in and around a slope. There are too many scenarios to cover in a single article, but here are a few tips to help keep operators, machines and crew members safe:
- Only allow your best operators to work on steep slopes. Safe operation in this environment relies on operator skill.
- Take weather conditions into consideration. Wet conditions may limit the available traction and prohibit you from working on a steep incline.
- Proper traction is essential. Even with the steel track grousers, there is only so much traction available. Ground-to-track shoe traction is a limiting factor for safe operation. If the machine slides toward the bucket when you dig parallel to the tracks while pointed downhill, the slope and ground conditions are too steep for safe untethered operation.
- Orientation of the tracks is critical. Make sure the tracks are pointed up and down the slope, not sideways. If you are working uphill, you want the idlers forward. If you are working downhill, you want the idlers pointed down slope. The idlers are designed to take the digging forces of the machine and spread them through the frame via the through axles connected at both points.
- Make use of any options, such as dozer blades. If the excavator is equipped with a front-mounted dozer, use it pointed downhill and pushed into the ground for grip against slipping. Do not raise and operate the machine up on the dozer structure. This is hard on the dozer linkage and reduces the traction of the track shoes.
- Be wary of operating on fill dirt. Often, it is tempting to use a wheel loader to bring in fill dirt so an excavator can sit level, such as an application on a mountain road. The problem is that as the machine operates, the fill dirt can shift and the excavator can become unstable.
John DeereUse attachment weight and boom position for stability
When moving the excavator, always make sure the tracks are pointed downhill and use the weight of the attachment to your advantage.
When going uphill, keeping the attachment out and forward will better balance the machine and aid traction and stability. Always keep the attachment low to the ground. Never travel up or down a slope with the attachment folded in and up. Dangerous loss of rearward stability will result and a rear rollover is possible.
Stretch the bucket and boom out and get the weight of the bucket and weight of the boom well forward of the machine, then walk your way up. If needed, put the bucket teeth in the ground and use the arm to help pull the machine up. Be ready to sink the bucket teeth in the ground if the excavator starts to slide. You can utilize the bucket and the teeth to stop the machine from moving and actually help pull you up the slope.
No substitute for operator skill
Pulling the machine up the slope with the boom and arm requires coordination. If the tracks are slipping due to a loss of traction, be aware that when you move the bucket teeth back out for another pull, the machine could slide backward. Stopping the travel function before lifting the bucket can help. It gives the tracks a better grip than they have while moving and sliding on slippery ground.
Don’t try to power up the slope with the travel motors while re-positioning the boom and arm. You’re apt to slide a little bit, especially if you have triple bar grousers. This takes a skilled operator. It’s not someplace you want to send a newbie.
Boom and attachment position can also help mitigate stability issues when descending a slope. Going downhill, roll the arm perpendicular to the boom or slightly out, level the bucket, keep the bucket just off the ground but not dragging, and point the attachment downhill. This will aid quick reaction to control the machine if it begins to slide. Never back down a slope as you need the attachment in front in case the machine slides.
Negotiating drop-offs requires operator expertise. If the slope begins with a sharp edge, the boom and bucket may be lowered over the side to control the machine and prevent a quick tip over the edge. The attachment can then slowly lower the machine to the slope.
Keep the machine steady as you traverse a slope. Do not swing the machine while traveling on a slope or loss of traction for one track could result.
Always be aware of your position
If you have to dig a trench while on a slope, be aware of the boom and arm position. When swinging, you want to have the boom and arm in fairly close to the machine. When you come out of the hole, you want to bring the mast in toward the machine so the swing torque will allow the machine to swing. If the mast is stretched all the way out, the momentum to swing is pretty significant. Bringing the boom and arm in and pulling the mast toward the swing bearing will assist the machine in swinging.
Take caution when swinging downhill. You want to be very gentle on the swing motor. When you come off that motor with a full bucket, if it is a big enough bucket and heavy enough material and you are too far out on the arm, the momentum and weight will overcome the swing brake.
Operators really need to develop a feel for the controls when digging on a slope. When you are on a hill, adjust how much effort you put into the controls. An unskilled or new operator can get into trouble in a hurry.
When working on slopes, the importance of simple safety devices such as the seat belt are amplified. Modern excavators are equipped with ROPS operator cabs. These are of limited use if the operator does not use the seat belt. Seat belts on a slope also aid in machine control, as the operator does not have to fight the angle and gravity to sit in the operator’s seat.
Don’t exceed machine lubrication limits
There are physical limitations on a slope due to the typical engine configuration. Generally, an excavator should not be operated beyond a 70% slope due to engine lubrication requirements. Some deep oil pans might allow engine lubrication at greater angles, but you are needlessly risking not only the engine lubrication issue, but traction to the ground.
This situation is not unique to any particular manufacturer. Pretty much every engine in the industry is limited to a 30° or 70% slope for lubrication of the engine. If you look at the spec sheets of pretty much every excavator brand across the board, the engine is limited to that gradation.
Make sure you are not exceeding that gradation for long periods of time. If you have a short duration where you climb a 1:1 slope, that is typically not bad. But if you are on that steep a slope too long, you have to take precautions to protect the engine. You can take the machine on much more severe slopes if you equip the excavator properly. That would be done through the dealer.
A key limitation is the depth of the sump. It only has so much depth, so there is only so much oil. When you are on severe slopes, it is hard for the engine to pump that oil to the very top of the motor. This results in starvation to the top of the engine. Be aware that continually operating on steep slopes can reduce engine life expectancy.
Maximize available traction
With traction being a primary limitation, every effort should be taken to maximize the traction available. Single grouser pads should be strongly considered for traction and safety.
The single bar grouser is like a dozer track. It penetrates for traction and will help hold the excavator on the slope. Triple bar grousers are good for flat and reasonable slopes. But as you get into 1:1 and sometimes steeper slopes, they will slide when you start trying to work.
Pipeline contractors working on steep inclines will often “yo-yo” the excavator once they get into that 1:1 category. They will connect the excavator to a cable dozer or two and suspend it below. This requires some properly completed safety modifications. In addition to modifications in the operator’s cab — such as a five-point harness and sometimes pedals or a pad placed on the posts so the operator can hold him/herself in the seat — a safe place is required to attach cables to the excavator. A lower frame-mounted tow hook or loop would be useful to help secure the machine to a dozer or similar machine. Do not sling around the lower structures. Too many sharp edges can damage them.
Factor in the strength of the rope supporting the excavator, as well as the security of the anchor point on the other end of the wire rope — such as to the front-mounted winch of a dozer with blade buried in the ground or rear winch with tracks buried in the ground. Do not tie to a tree. Tying to a tree of unknown structure is not safe.
Information for this article was provided by John Deere, Hitachi and Kobelco.