Safe Mast Operation & Winch Clutch Adjustment
Applies to: MT81-13KWH and MT81-6KWH Security Trailers
MT81 Security Trailers use a powered winch to raise and lower the trailer mast. The winch clutch must be calibrated for the weight of the devices mounted on the mast. This guide covers safe mast operation, clutch calibration, and recovery procedures for a stuck mast or improperly routed cable.
Recalibrate the clutch whenever the device loadout on the mast changes.
Operating the mast
Before raising the mast
Confirm the winch clutch is calibrated for your device loadout. If you have added, removed, or changed devices on the mast since the last calibration, complete the clutch calibration procedure before raising the mast.
Check overhead clearance. Survey the area above and around the trailer before positioning it. Never raise the mast near overhead power lines. Contact with power lines can cause electrocution. Maintain at least 10 feet (3 m) of clearance from any power line, and account for the mast's full extended height, up to 24 feet, plus any equipment mounted on top.
Check the weather. Do not raise the mast in high winds or when storms or lightning approach. Consult your trailer's datasheet for its maximum wind speed rating.
Position on firm, level ground. Never raise the mast on uneven or soft ground. Chock the wheels, deploy all outriggers and leveling jacks, and confirm the trailer is level using the built-in level indicator before proceeding.
Inspect the equipment. Check the winch cable for fraying, kinks, corrosion, or crushed strands. Check the pulleys, mast sections, and locking hardware for damage. Do not raise the mast if you find any damaged or obstructed components. Tag the trailer out of service and repair it first.
Secure mounted equipment and cabling. Verify that all devices on the mast are securely attached. Before and during mast adjustment, check that the winch cable runs straight and cannot become pinched — either by equipment, hardware, or mast sections, or by coiling or looping back on itself.
While raising or lowering the mast
Keep all personnel clear of the area around and beneath the mast during raising and lowering.
Keep tension on the winch cable at all times. Never allow slack in the cable. Slack can cause the cable to jump the winch drum or pulley, or cause a mast section to drop suddenly when the slack is taken up.
Raise and lower smoothly. Stop immediately if you feel the cable binding, hear unusual noises, or see it behaving abnormally. Do not force the winch.
Do not exceed the extension limit. Do not extend the mast higher than necessary for your environment. Stop the winch when all mast sections are fully extended and the cable reaches the end of its travel.
Lock the mast rotation by tightening the rotation-lock knob(s) once the mast is positioned.
While the mast is raised
Never move or tow the trailer while the mast is extended. Fully retract and secure the mast before repositioning the trailer, even for short distances.
Lower the mast if conditions change, such as when high winds, storms, or lightning approach.
If the mast becomes stuck
Clear the area. Keep all personnel away from and out from under the mast until you resolve the issue.
Do not shake, strike, or climb the trailer or mast to free it. A stuck mast may hold stored energy and can drop without warning.
Follow the recovery procedure below. Contact Verkada Support immediately to go through the recovery procedure — do not attempt any other repair, and never work under or near a stuck mast.
After lowering
Fully retract and secure the mast and confirm all locks and travel restraints are engaged before stowing outriggers or moving the trailer.
Calibrating the winch
Read this guide in its entirety before taking any action.
Ensure all personnel are clear of the area below the mast before adjusting the winch clutch. Never adjust the winch clutch with the mast raised. Unless you are a Verkada Qualified Trailer Partner, always contact Verkada Support before attempting winch calibration.
Symptoms of clutch issues
Mast leans when extended
Unspooled or loose cable on the winch wheel
Mast stuck (will not raise or lower)
Mast slips while raising or lowering
1. Understand the correct clutch setting
The correct clutch setting depends on the weight mounted at the top of the mast. Heavier head loads require a tighter clutch nut. Use the following criteria to evaluate the setting during adjustment:
Too loose: The mast cannot extend because the clutch slips before it lifts the load.
Too tight: The clutch never slips, even at full extension. The winch continues to pull against the fully extended mast, which can overload the cable, winch motor, or mast hardware.
Correctly adjusted: The mast raises fully through the entire stroke, and the clutch begins to slip only when the mast reaches full extension.
The slip point is the key indicator: the clutch should carry the load through the full height and slip just as the mast reaches its limit.
2. Adjust the winch clutch
Clear the area. Confirm no personnel, tools, or obstructions are below or around the mast.
Lower the mast until less than 2 inches (5 cm) of clearance remains between the mast collar and the base plate.
Locate and remove the access cap on the winch housing.
Pry it off with a flathead screwdriver.
Ensure the clutch nut is behind the cap.
Loosen the clutch nut using a 3/4″ socket and ratchet.
Adjust the clutch nut in 1/8-turn increments. Turn clockwise to tighten the clutch and counterclockwise to loosen it. After each adjustment:
Test mast operation against the criteria in Section 1. Initially, raise and lower the mast in increments of 5 feet (1.5 m) or less.
Fully lower the mast before making any additional adjustments.
3. Verify cable routing
Whenever you adjust the clutch, inspect the winch cable and confirm it is properly routed and seated in the winch wheel. Improper routing can mimic clutch problems and cause binding or cable damage.
If the cable is routed incorrectly, complete the recovery procedure below before continuing.
Recover from improper cable routing
This procedure requires two people: one to operate the winch switch and one to guide the cable.
CAUTION: Keep hands clear of the winch drum, wheel, and pulleys while the winch is in motion. Wear gloves when handling the cable, and grip the cable only at a safe distance from the winch.
Raise the mast. The first person operates the winch switch while the second person pulls excess cable away from the winch so it can unwind properly. If the cable becomes stuck while raising the mast, the first person must stop immediately. Lower the mast and have the second person adjust the cable to clear the blockage before continuing.
Fully extend the mast and confirm that the cable moves freely. Then lower the mast while guiding the cable into the correct routing on the winch wheel.
Verify the cable routing by running the mast through a full up/down cycle. Confirm that the cable remains properly seated in the winch wheel.
4. Validation & return to service
Repeat Sections 2 and 3 as needed, adjusting in 1/8-turn increments. Always fully lower the mast before making additional adjustments, and verify cable routing while raising the mast.
Once the correct clutch setting is found, run the mast through a full up/down cycle. Confirm:
Smooth extension and retraction through the entire stroke
Clutch slip occurs only at full extension
Cable is properly routed and seated in the winch wheel
Reinstall the access cap on the winch housing and confirm it is fully seated.
Return the unit to service.
5. If issues persist
If the mast still exhibits stability issues after clutch adjustment and cable routing checks, Contact Verkada Support for further assistance.
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