If you’ve ever stood at the base of a double mast aerial work platform (DWAP) preparing to send a technician 30 feet in the air, you know that trust isn’t something you guess—it’s something you verify. As a supplier of DWAPs, I’ve spent thousands of hours walking new operators and rental technicians through pre-use checks, and I can tell you: skipping even one step here isn’t just a workflow shortcut—it’s a safety risk that can turn a routine job into an emergency. Over the past 12 years, I’ve seen too many near-misses and too few documented checks, so let’s break this down like we do for our own service techs: no jargon, no fluff, just the exact steps to confirm your DWAP is ready to work, every single time. Double Mast Aerial Work Platform
First, let’s get one thing straight: a double mast aerial work platform isn’t a single machine—it’s two vertical masts working in sync to lift a platform, with hydraulics, controls, bearings, and safety interlocks that all have to be operating in lockstep. The biggest mistake new operators make is treating this like a single-mast scissor lift; the dual masts add unique failure points, and we’ve designed our units with extra safety features to catch those—if you know where to look. I start every pre-use check at the “big picture” level, not diving into small parts first, because a quick visual scan can rule out 70% of issues before you even touch a tool.
Let’s start with the exterior and base inspection. This is the part you can do in 60 seconds before climbing into the control cabin, and it’s non-negotiable. First, walk the full perimeter of the DWAP to check for visible damage. Look at the two masts: any cracks in the welds (especially at the base where the masts connect to the chassis) or bent sections of the mast tubing are red flags. I once had a customer who skipped this step and tried to use a unit with a bent mast—when he lifted the platform 25 feet up, it leaned 12 inches to one side, and his technician had to climb down manually because the tilt sensor kicked in. The bent mast had been caused by a previous operator driving the unit over a curb, and it was just hidden by dirt until someone got on their knees to check the base. Next, check the chassis and outriggers: double mast units rely on outriggers to distribute weight when lifted, so make sure every outrigger is fully extended, the pads are not cracked or worn, and there’s no dirt or debris trapped under them that could make them unstable. If even one outrigger is partially extended, do not operate the unit—our units have a tilt interlock that will disable the lift function, but I’ve seen that interlock bypassed, which is never a good idea. Finally, check the tires (if your DWAP is mobile): any cuts deeper than a quarter inch, low pressure, or uneven wear can make the unit unstable on uneven ground, especially when the platform is at full height.
Next, move to the power and hydraulic systems, which are the heart of the DWAP. The masts move hydraulically, so any issue here can cause a sudden drop or stall mid-lift. First, check the fluid levels: hydraulic fluid should be at the marked line on the reservoir, and the color should be clear amber, not dark or milky. Dark fluid means it’s contaminated, and milky fluid means there’s water in the system—both will damage the hydraulic pump and cause the masts to stall. Next, inspect all hydraulic hoses and fittings: look for any cracks, bulges, or leaks. A small leak might seem insignificant, but when you’re lifting 500 pounds of personnel and tools 30 feet in the air, a burst hose can send the platform plummeting. We recommend replacing hoses every 5 years regardless of appearance, but a quick pre-use check will catch any immediate issues. Then, test the power supply: if your DWAP is electric, check the battery terminals for corrosion, make sure the charge is at least 80% (most units have a gauge on the control panel), and test the emergency stop button at the base and in the platform—every operator knows this, but you’d be surprised how many times a sticky emergency stop is missed until it’s needed. If your unit is hybrid or diesel-powered, check the fuel level (and make sure it’s the right type for the unit), inspect the engine oil and coolant levels, and test the engine start and shut-off functions.
Now, the most critical part for a double mast unit: the mast synchronization and bearing inspection. Unlike single-mast units, double masts have to move at exactly the same speed to keep the platform level and stable. If they get out of sync, the platform can tilt, putting too much stress on one mast and causing a failure. First, look at the mast guides: these are the plastic or metal pieces that keep the masts aligned as they move, and they wear out over time. If the guides are cracked, worn down, or missing, the masts will rub against each other, cause extra friction, and can get stuck mid-lift. Next, test the synchronization: you don’t need to lift the platform full height to do this—just lift it 2-3 feet off the ground, then turn it off and check if it settles evenly. If one mast drops faster than the other, that’s a synchronization issue that needs to be fixed before use. We have a service technician who once tested a unit and found the masts settled 4 inches apart, and upon inspection, one of the mast drive gears was stripped—if he’d skipped that check, the platform would have tilted 10 degrees at full height, which is enough to cause a fall hazard. Also, check the mast bearings: these are the parts that let the masts extend and retract smoothly, and they should be greased according to the unit’s manual. If you hear grinding or squeaking when the masts move, that means the bearings are dry and need to be greased—operating a DWAP with dry bearings can cause permanent mast damage.
Next, safety interlocks and controls—these are the fail-safes that keep everyone on the ground and in the platform safe, and there should be no exceptions here. Let’s start with the platform controls: get in the platform and test all functions—up, down, tilt, rotation (if applicable), and the emergency stop in the platform. Then, go back to the base control panel and test all the same functions from there. The two control panels should work in sync, and the base panel should lock out the platform controls when activated (that’s a feature we built into all our units to prevent accidental operation when servicing). If the lockout doesn’t work, that’s a major issue—only the base should have control when someone is working on the unit. Next, test the tilt and overload sensors: these are the two most important safety features on a DWAP. The tilt sensor will shut off the lift function if the unit is too unstable, and the overload sensor will stop the lift if the platform exceeds its weight limit (usually 500 or 1000 pounds, depending on the model). To test the tilt sensor, gently tip the unit with a pry bar (or use the built-in tilt test function, if your unit has one) and make sure the lift shuts off immediately. Never bypass these sensors—we’ve had customers who thought the sensor was too sensitive and disabled it, only to have the unit tip over on uneven ground. For the overload sensor, check the calibration sticker on the unit—most need to be calibrated annually by a certified technician, but a quick pre-use check can confirm it’s not triggering unexpectedly when the platform is empty. Finally, check the guardrails and fall protection: the platform guardrails should be intact, no missing bolts or bent rails, and the gate should latch securely. Any fall protection devices (like lanyard anchors) should be in good condition, no fraying or cracks in the anchor points.
Wait, one more step that most operators forget: the pre-operation log. Our company provides a daily pre-use log with every DWAP we sell or rent, and we require operators to sign it before using the unit. This isn’t just paperwork—it’s a way to track issues over time. If an operator signs the log saying everything is fine, but another operator later finds a leak, we can check the previous logs and see when the leak started, instead of realizing it after a failure. We also share log templates with all our clients, and we recommend taking photos of any issues you find so the service team can fix them quickly. Last year, a customer used our log to track a small leak in the hydraulic hose, and we replaced it before it caused a major problem that would have taken the unit out of service for a week.
Let me wrap this up with a real example that stuck with me. A construction company rented three of our double mast units last spring, and their operator skipped the mast synchronization check. When he lifted the platform 30 feet, the masts got out of sync, the platform tilted, and he had to call the fire department to lower him—he spent 4 hours stuck in the air, the unit was damaged beyond use for 10 days, and they had to pay overtime for the fire department. If he’d spent 2 minutes checking the synchronization before lifting, that whole situation would have been avoided.
At the end of the day, checking the safety status of a double mast aerial work platform before use is about two things: protecting your team and protecting your business. I’ve spent my career building these units, and I can tell you that every one of our DWAPs is designed with safety as the top priority—but that only works if you take the time to verify every part before turning the key. If you have questions about our DWAP models, need a training session for your team, or want to learn more about regular maintenance schedules, don’t hesitate to reach out to our team to discuss your needs. We’re here to make sure your aerial work is safe, reliable, and successful, every single time.
Sleeve Type Aerial Work Platform References
OSHA 1926 Subpart L: Scaffolds, Aerial Lifts, and Other Fall Protection Equipment. Occupational Safety and Health Administration, U.S. Department of Labor, 2023.
ANSI/SIA A92.5: American National Standard for Mobile Elevated Work Platforms – Design, Calculations, Requirements, Tests, and Acceptance Criteria. Association for Advancing Automation, 2022.
Manufacturer’s Operation and Maintenance Manual: Double Mast Aerial Work Platforms. Our Company Name, 2021.
Mantall Heavy Industry Co., Ltd.
Mantall Heavy Industry Co., Ltd. is well-known as one of the leading double mast aerial work platform manufacturers and suppliers in China, featured by quality products and good service. Welcome to buy discount double mast aerial work platform made in China here from our factory. For pricelist and quotation, contact us now.
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