How do excavator, backhoe and skid steer controls work? ISO and SAE patterns

Safety first: before you move a control

No machine is driven “to see how it responds”. Each model's operator manual is what rules, and they all repeat the same thing before the first lever:

• Do the walk-around and climb up with three points of contact.
• Sit down, adjust the seat and buckle the seat belt.
• On a skid steer, the seat bar down; on an excavator, the lock lever in LOCK until you're ready, released slowly.
• Confirm which control pattern the machine uses (ISO or SAE) before touching the joysticks.
• Nobody inside the swing radius or in the machine's path (the Bobcat E35 mini excavator manual asks for 6 m); before swinging, look where you're swinging.
• Try each control slowly, with the equipment near the ground, in a clear area.
• When getting off: attachment on the ground, lock on (on Bobcat mini excavators, the console raised), engine off and the key with you.

• Safe operation and good use of machinery: the operator's rules
• Daily inspection before operating a machine: the complete checklist

Excavator: what each joystick moves (ISO pattern)

An excavator has four work-equipment movements —boom, arm, bucket and swing— shared between two joysticks. Each joystick does two things: one forward and back, another side to side. That way movements can be combined, which is what makes a good operator's work smooth.

With the ISO pattern, the one most excavators come with from the factory:

• Left joystick, forward and back: the arm goes out and in.
• Left joystick, side to side: the upper structure swings left or right.
• Right joystick, forward and back: the boom lowers and raises.
• Right joystick, side to side: the bucket curls in or dumps.

ISO or SAE: the difference and how to tell which one your machine has

Both patterns move the same things; what changes is the hand. In the ISO pattern, the boom is on the right joystick and the arm on the left. In the SAE pattern, the backhoe pattern, the boom is on the left and the arm on the right. Swing and bucket stay where they were. Each manufacturer names it its own way: the Bobcat E35 mini excavator manual calls SAE “STANDARD” (STD), and Komatsu calls it the backhoe (BH) pattern.

An operator who learned on one pattern and climbs onto a machine with the other will move the boom when they meant to move the arm. That's why some machines have a pattern selector —on the Bobcat E35 it's a lever under the seat; Komatsu offers a pattern change valve on models such as the PC170LC-11— and why it's never assumed: before working, read the manual, find the pattern decal in the cab and try each movement slowly with the equipment near the ground. The pattern is switched the way that machine's manual says, never in the middle of the job.

How an excavator travels

The tracks move with two levers, one per track, which usually have pedals too: that's how the PC210-10M0 comes, per its datasheet. Both forward: it goes straight. Just one: it turns on the track that stays still. One forward and one back: it spins on its center.

Careful: the travel levers follow the undercarriage, not the cab. Because the upper structure swings, the cab can end up facing the back of the undercarriage. Bobcat's mini excavator manual puts it this way: before traveling, check where the blade is; if the blade is at the rear, the levers and pedals work the opposite way to when the blade is in front. Each manual says what its machine's reference is: find it before moving the tracks.

• What are the parts of an excavator and what does each one do?
• How to choose an excavator (and what size you need)

Backhoe loader: two stations in one cab

Facing forward you drive the tractor and run the loader: steering wheel, throttle and brake pedals, the forward-reverse lever and the loader lever, which raises and lowers the front bucket and tilts it to fill and dump.

To dig, first park, lower the front bucket to the ground and lower the two stabilizers with their levers. Then swivel the seat to the rear: that's where the backhoe controls are, moving the boom, dipper, backhoe bucket and swing. Depending on the model they're levers or joysticks: on the WB93R-5E0 the backhoe has mechanical levers and PPC joysticks are optional, and on the WB97R-5E0 PPC servo controls are standard for the loader and the backhoe, per their datasheets. The excavator rule applies all the same: confirm the pattern before digging.

• What are the parts of a backhoe loader and what does each one do?
• How do you choose a backhoe loader for your jobsite?

Skid steer: levers, pedals or joysticks

A skid steer has no steering wheel: each side has its own drive. To turn, one side goes faster than the other. On Bobcat, standard controls are two hand levers to drive and steer, and two foot pedals to raise the arms and tilt the bucket. With Selectable Joystick Controls (SJC), the operator picks the pattern with a switch in the cab: in the ISO pattern, the left joystick handles travel and the right one the arms and bucket; in the H pattern, each joystick handles the drive on its side, and the left one also raises the arms while the right one tilts the bucket. Careful: skid steer “ISO” is not excavator “ISO”.

The Komatsu SK820-5E0 comes with PPC joysticks: the right one moves the arms and bucket, and the left one handles travel, per its datasheet.

The seat bar is part of the controls. The Bobcat S590 manual asks you to operate with the seat belt fastened and the bar down, and on the SK820-5E0 the safety system leaves everything motionless if the bar is raised or the operator isn't seated, per its datasheet. Get in and out always with the arms down and the attachment flat on the ground.

• What are the parts of a skid steer loader and what does each one do?
• How do you choose a skid steer: radial or vertical, wheels or tracks?

Reading isn't driving: where you learn

Knowing what each control moves is the first step, not the last. Combined movements, reading the ground and working near trenches, slopes and people are learned with an instructor, first on a simulator and then in the field.

Grupo ConstruMarket's APMT Academy runs the Basic Hydraulic Excavator Operation Course with safety and operation theory, simulator practice and real-field practice, in El Salvador and Nicaragua.

• How do you become a heavy equipment operator, and where can you train in Central America?