Hydraulic Small Excavator – How It Works in Different Working Conditions

A hydraulic small excavator does four main things: digs, lifts, swings, and moves. Each action puts different demands on the hydraulic system – some need full power, others need speed, and many require both at the same time. Here's what happens inside the machine during each working condition.

Four Main Actions – Four Different Hydraulic Demands

A hydraulic small excavator performs four primary actions during a typical work cycle: digging, lifting and swinging, dumping, and returning. Each action places a different load on the hydraulic system, and the machine's performance depends on how well the hydraulic components respond to those changing demands.

Here's a breakdown of what happens in each working condition – and what it means for the operator. Browse our small excavator lineup to see the models available for your job site.

1. Digging – Bucket and Stick Work Together

Digging is where the real work happens. The operator uses the bucket cylinder, the stick cylinder, or both together to break into the ground. This is typically a combined action – the bucket curls while the stick pulls back, and sometimes the boom lowers to help penetration.

What the hydraulic system does: During digging, the hydraulic system needs high pressure to generate enough force to break through soil or rock. The pump delivers maximum flow to the cylinders, and the system adjusts pressure based on the resistance encountered. Harder ground means higher pressure.

What operators should know: Digging puts the heaviest load on the hydraulic system. If you hear the relief valve opening constantly, you're pushing too hard – back off slightly and let the machine work at its own pace. Overloading the system wastes fuel and wears out components faster. Learn more about digging with small excavators for practical trenching tips.

2. Lifting and Swinging – Boom and Swing Motor in Sync

Once the bucket is full, the boom cylinder lifts the boom while the swing motor rotates the upper structure toward the dump truck or stockpile. This is a combined action of the boom and the swing motor – two different hydraulic circuits working at the same time.

What the hydraulic system does: Lifting requires high pressure to hold the load. Swinging requires flow to move the turntable at a controlled speed. The hydraulic system must balance pressure and flow between these two functions. If the pump can't supply enough flow to both, the swing slows down or the boom lift stalls.

What operators should know: Smooth operation matters here. Jerky movements waste time and put extra stress on the swing motor and boom cylinder. Use gradual joystick inputs – the machine responds better and the hydraulic system stays cooler.

3. Dumping – Stick and Bucket Position the Load

At the dumping point, the operator brakes the turntable, adjusts the unloading radius with the stick cylinder, and retracts the bucket cylinder to dump the load. The boom cylinder may also be used to fine-tune the dumping height.

What the hydraulic system does: Dumping is less demanding than digging or lifting. The system primarily needs precise control rather than high power. The pump delivers lower flow at moderate pressure, allowing the operator to position the load accurately.

What operators should know: This is where precision matters more than power. Rushing the dump cycle often leads to spillage or incomplete unloading – which means extra cycles to clean up. Take the extra second to position the bucket correctly.

4. Returning – Swing and Boom Reposition the Empty Bucket

After dumping, the turntable rotates back toward the digging face, and the boom and stick cylinders lower the empty bucket to the new digging position. This is typically a combined action of rotation and boom or stick movement.

What the hydraulic system does: Returning is the least demanding part of the cycle. The hydraulic system operates at lower pressure and flow, since there's no load in the bucket and the machine is just repositioning.

What operators should know: This is where speed matters. A fast return cycle means more digs per hour. But don't sacrifice control – swinging too fast with the bucket raised is a stability risk, especially on uneven ground.

What This Means for Your Daily Operation

The hydraulic system is the heart of a small excavator. Understanding how it responds to different working conditions helps you operate more efficiently and avoid unnecessary wear:

• During heavy digging: Let the machine work – don't force it. Constant relief valve operation wastes fuel and heats up the hydraulic oil.
• During lifting and swinging: Smooth joystick inputs reduce stress on the swing motor and boom cylinder.
• During dumping: Precision saves time – accurate positioning means fewer cleanup passes.
• During returning: Speed helps cycle time, but keep the bucket low to maintain stability.

A well-maintained hydraulic system responds smoothly and consistently across all working conditions. If you notice sluggish movements, unusual noises, or inconsistent power, it's time to check the hydraulic fluid level, filters, and pump condition.

Frequently Asked Questions

What are the main working conditions of a hydraulic small excavator?

The four main working conditions are digging, lifting and swinging, dumping, and returning to the digging position. Each condition puts different demands on the hydraulic system – digging needs high pressure, lifting and swinging need balanced pressure and flow, dumping needs precision, and returning needs speed.

Why does my excavator feel sluggish during combined actions like lifting and swinging?

During combined actions, the hydraulic system must divide flow between multiple circuits. If the pump can't supply enough flow to both functions, one action will slow down. This is normal on smaller machines with limited pump capacity. Smoother joystick inputs help the system balance flow more effectively.

What causes the hydraulic system to overheat during continuous digging?

Continuous heavy digging keeps the hydraulic system at high pressure for extended periods, which generates heat. If the hydraulic oil temperature exceeds 80°C (176°F), check the oil level, clean the cooler fins, and verify that the relief valve isn't stuck open.

How does ground condition affect hydraulic performance?

Hard or rocky ground requires higher hydraulic pressure to break through, which puts more strain on the pump and cylinders. Soft or muddy ground reduces traction, which can make the machine feel less responsive even though the hydraulic system is working normally.

What's the most common mistake operators make in different working conditions?

Pushing too hard during digging – it doesn't speed up the work, it just heats up the oil and wears out the components. Let the machine dig at its own pace and use the hydraulic power efficiently.

Not sure which excavator fits your work? Read our buying guide to find the right model for your job site.