Terex AC500-2 Pre-Use Checklist: What to Check Before the Lift (And What Drift Actually Means)

If you are about to put a Terex AC500-2 on a critical lift, you need a simple field checklist before the rigging show starts. I coordinate emergency crane work for contractors, so I am the person who gets the phone call when a crane is not ready. This is the checklist I use. It is not load chart training. It is the stop-doing-dumb-things list before you trust 500 tonnes of steel arm with something expensive.

Here is what you need to know up front: drift is the most common field issue I see on all-terrain cranes. And on the AC500-2, the Terex TITAN control system gives you a lot of data, but it does not stop the machine from drifting. That part is still on you.

What Is Drift? (The Quick Answer)

Drift is movement of the boom, hook, or load after the operator moves the joystick back to neutral. It happens when hydraulic oil bypasses a valve, a cylinder seal, or a counterbalance valve. On the AC500-2 you usually see it as:

• Boom angle slowly decreasing while the boom is supposed to be held in place.
• Hook or block slowly descending with the winch brake supposedly engaged.
• Swing drifting after you release the swing control, especially in wind.
• An outrigger bleeding down, which changes the level of the machine.

Drift is not the same as a planned lower or a controlled crawl. Planned controls stop movement when you release them. Drift does not.

I also want to be clear about one thing before the checklist: I am not a Terex factory rep. This is field practice, not a replacement for the operator's manual. If your manual or ASME B30.5 says something different, the manual wins.

The 7-Point AC500-2 Pre-Lift Checklist

Use this in order. The list is simple, but it works. If you only have 20 minutes before the truck arrives, use them on this.

1. Start the machine and go through the TITAN control screens

Turn on the machine, let the screen boot, and check for fault codes. The Terex TITAN controls on the AC500-2 show system warnings, load data, and the rating display. If a search like terex titan controls ark brought you here, you are looking for that rating display in the TITAN system. It tells you allowable load and radius. It does not tell you if the boom is drifting.

Check the fault log. If there is a stored sensor fault, treat it as a red flag, not a mystery. Find out why it happened before putting a load on the hook.

2. Warm up the hydraulics before testing drift

The step I see skipped on almost every rushed job is the warm-up. Cold hydraulic oil can hide a worn valve. A crane can sit overnight, hold a load perfectly, and then drift after the oil warms up and thins out. I once saw an AC500-2 pass a cold drift test and fail a warm one 30 minutes later.

Before you check anything, run the engine at operating speed, cycle each function through its full range, and get the fluid temperature into the normal working range. (Mental note: this is the boring 15 minutes that saves the scary phone call.)

3. Set up on solid ground and fully extend the outriggers

Drift can show up as an outrigger bleed, not just a boom leak. If the machine is on rubber or on a pad that is not solid, you will not get a clean test. Extend the outriggers, set all floats, and use the level system to get the machine level. Then watch the indicators for a couple of minutes. If any outrigger moves after setup, you just found a problem before the load did.

4. Run an empty hook drift test

Position the boom at the radius that matters for the job, or as close to it as the setup allows. Raise the boom to the planned angle. With the hook empty, run the hoist up a few feet, then bring all controls back to neutral. Watch the load block and the boom angle for five minutes.

If the hook starts to drop, or the boom angle keeps changing, do not ignore it because the load management system says you are within capacity. Drift can take the crane out of its approved setup, even if the original radius was inside the chart. A drift that starts at three meters can move the radius past the load chart limit before the load is in the air.

Use a tape measure or a marked stick near the block so you can see small movement. A phone video with the TITAN display in the frame gives you evidence if you need to call the rental company.

5. Test on the main functions used by the lift

Not all drift is the same. A crane can have a perfect hoist and a bad boom-hoist cylinder. The drift test needs to cover the functions you will actually use: main hoist, boom up and down, telescoping, and swing. If the placement is high precision, the swing brake and the hoist brake are both critical. (In my book, skipping this is a deal-breaker.)

6. Check the load chart for the real working radius

Every AC500-2 has a load chart, and every job seems to have a plan that starts with the wrong page. Do not plan a lift from the maximum capacity number. Look at the chart for the exact radius, boom length, counterweight configuration, and rigging allowance for your lift. This includes the hook block weight and any spreader bars. They eat into capacity, and the load management system will show that, but you should know it before the lift plan is approved.

If you are near 90 percent of chart capacity, that is too close for comfort when drift or wind is a factor. I do not have a magic number from the factory for every situation. In the field, the goal is a buffer, not to squeeze every kilogram out of the machine.

Look at the total cost of the lift, not just the ticket price. A cheap rental that drifts is not cheap. The TCO of a critical lift includes the rental rate, the operator's time, the service call, the schedule delay, rework, and risk. I have watched a one-hour drift check save a much bigger problem. That is the cheapest hour in the budget.

7. Record the test and report any movement

Take a video of the drift test. Show the TITAN display, the measuring point on the block, and a tape measure or sticker. If the boom or hook moves more than the maintenance manual allows, call the rental company or service department immediately. Do not try to compensate with the controls during a real lift. That is how bad jobs happen.

If the movement is only a few millimeters and then stops, that might be normal. If it keeps moving, it is a problem. Eddie Groves, the operator I send to the worst sites, says it best: a crane that is drifting is telling you something before you ask it to do the hard part. Listen to it.

What the Load Chart Does Not Tell You

The load chart assumes the machine is in good condition, level, and not drifting. The TITAN control system uses pressure sensors, length sensors, and angle sensors to calculate capacity. But if a cylinder is leaking internally, the angle sensor will eventually see the drift, but by then the radius has changed. The system did not cause the problem, and it cannot warn you until the data tells it something is wrong.

In March 2024, a contractor called me late at night after their planned 500-tonne crane was not ready. We found a low-hour AC500-2 that looked clean, but the empty hook test caught a failing counterbalance valve on the main boom. A service tech swapped it in a few hours. The after-hours service cost real money. It was a lot less than the schedule penalty would have been. So glad we ran the test before the load was anywhere near the hook.

Common Mistakes That Cost More Than the Rental

• Testing drift with cold oil. You did not test anything except a sticky machine.
• Testing with an empty hook and then assuming the load will be fine. The empty hook is the minimum. If you have time and safe conditions, test at the planned load or close to it.
• Skipping the warm-up cycle because the operator is in a hurry. That is exactly when the crane will decide to teach you a lesson.
• Trusting a load indicator to catch what you should catch before the lift. The indicator is a tool, not a safety net.
• Forgetting that an outrigger can drift too. I knew I should check the outrigger cylinder during setup, but I thought, what are the odds? Well, the odds caught up with me on a long blind lift when one corner bled down an inch. It did not tip, but it ruined the whole day. That was the one time it mattered.
• Renting or hiring on price alone without asking the owner for the last maintenance record and drift test. If the owner does not know what drift is, find another machine.

There is something satisfying about watching the boom angle hold steady after a full drift test. It means the machine is ready. The controls are quiet, the load chart is checked, and the buffer is there. That is the payoff. That is what makes the extra 15 minutes worth it.

Bottom line: know what drift is, test for it before the lift, and do not let the TITAN controls talk you out of a physical check. The AC500-2 is a serious machine. Treat it like one.