What Strut Force Is Required for an Armored Vehicle Power Tailgate?

Adding ballistic armor to a vehicle tailgate can significantly increase its weight and change its center of gravity. As a result, the original power liftgate struts may no longer open, hold or close the modified tailgate safely.

The Short Answer

There is no universal strut-force specification for an armored vehicle tailgate.

The required force depends on the complete tailgate weight, armor distribution, center of gravity, hinge geometry, actuator mounting position and required operating speed.

In one armored Volvo XC90 project evaluated by TOMASTER, the target force values reached:

• F1 opening force: approximately 213 kgf / 2,089 N

• F2 closing force: approximately 337 kgf / 3,305 N

• (https://www.youtube.com/embed/xcGlbczyHaA?si=GJ-WYvJyiX-uqy0X)

These values represent a specific vehicle configuration and measurement method. They should not be treated as standard requirements for every armored XC90 or armored vehicle.

Why Does Ballistic Armor Increase the Required Force?

Tailgate operation is governed by torque around the hinge axis, not weight alone.

A simplified engineering relationship is:

Required hinge torque = load force × horizontal distance from the center of gravity to the hinge

Ballistic glass, steel armor and reinforcement components add mass to different areas of the tailgate. When this additional mass is positioned farther from the hinges, the actuator must overcome substantially greater torque.

Why Are OEM Power Liftgate Struts Insufficient?

OEM struts are designed around the original tailgate mass, balance and operating geometry.

After armor installation, the factory system may experience:

• Insufficient opening force

• Failure to hold the tailgate open

• Slow or interrupted movement

• Automatic reversal during closing

• Excessive motor current

• Gear or transmission wear

• Increased stress on hinges and mounting points

Simply increasing motor torque may transfer excessive loads into components that were not designed for them.

What Must Be Redesigned?

A reliable armored-vehicle power liftgate system may require:

• Higher-torque drive units

• Larger-diameter screws, gears or transmission components

• Reinforced actuator mounting brackets

• Stronger hinges and body mounting points

• Optimized actuator mounting geometry

• Revised motor-current and anti-pinch calibration

• Controlled opening and closing speed

• Reliable manual emergency operation

Why Stronger Struts Alone Are Not Enough

Installing higher-force struts without checking the complete structure may damage the hinges, brackets, tailgate frame or vehicle body.

Excessive assistance force can also make manual closing difficult and interfere with obstacle-detection or anti-pinch functions.

The correct solution must balance actuator force, structural capacity, movement control and safety protection.

Engineering Data Required Before Selection

Before selecting an electric tailgate strut, engineers should confirm:

• Complete modified tailgate weight

• Armor material and weight distribution

• Tailgate center of gravity

• Hinge-to-center-of-gravity distance

• Actuator mounting points and angles

• Required opening angle and operating time

• Vehicle slope requirements

• Available electrical current

• Structural and fatigue-test requirements

TOMASTER develops custom electric tailgate systems for armored, modified and heavy-duty vehicles. Final actuator selection is based on measured vehicle data and complete-system validation rather than tailgate weight alone.