When a boom lift works near steelwork, roof edges or pipe runs, its platform may have to pass very close to surrounding structures. If the operator misjudges the distance, they can become trapped between an obstruction and the platform controls.
The danger can increase if the trapped person cannot release the joystick—or makes unintended contact with it while being crushed.
Some boom lifts are equipped with secondary guarding, also called anti-entrapment protection, to reduce particular risks in such situations. But secondary guarding is not a universal obstacle-avoidance system, and it cannot guarantee that an operator will not be trapped or injured.
1. What is the system intended to do?
Imagine a platform moving towards a steel beam. The operator becomes pressed against the control area and cannot release the controls normally.
Depending on the design, a secondary-guarding sensor may respond to a specified contact or activation event. The machine may then stop relevant movement, sound a warning, briefly reverse certain functions, or apply restrictions until the situation is assessed.
These are possibilities, not a standard sequence across all brands. Detection methods, activation zones and the machine response differ from system to system.
2. JLG SkyGuard and Genie Lift Guard: two different responses
JLG SkyGuard: stop, then briefly reverse most applicable functions
JLG’s SkyGuard monitors contact with a sensor in the platform control area. On activation, it stops the active functions, sounds an alarm and can temporarily reverse most of the functions that were operating.
JLG describes this as reverse functionality. Some functions are excluded, and the precise response depends on the system and machine configuration. See JLG’s SkyGuard technical page.
The intended benefit is to reduce continued crushing in some circumstances. It does not mean the controller can identify a safe escape route through a cluttered work area. An automatic reversal may not resolve a complex entrapment.
Genie Lift Guard Contact Alarm: interrupt motion and alert others
Genie’s Lift Guard Contact Alarm uses an activation cable above the platform control panel. When contact disconnects the cable under the system’s defined conditions, lift and drive functions are interrupted and audible and visual warnings alert nearby people.
Genie’s original 2017 system information explains that movement does not simply resume on its own; human intervention is needed. See Genie’s official introduction and accessory description.
| Feature | JLG SkyGuard | Genie Lift Guard Contact Alarm |
|---|---|---|
| Typical trigger | Contact with a sensor near the platform controls | Activation cable above the controls is tripped |
| Machine response | Stops active functions; briefly reverses most applicable functions | Interrupts specified lift and drive functions |
| Warning | Audible alarm | Audible warning and flashing beacon |
| Primary approach | Reduce continued movement and, in some cases, move briefly away | Interrupt motion and alert nearby personnel |
| Guaranteed prevention of entrapment? | No | No |
This comparison describes the published systems cited here. Different models, production years and retrofit arrangements may respond differently; use the documentation for the exact machine and installed system.
The buyer’s real question is not which name sounds safer. It is what triggers the installed device, what the machine then does, and what must happen next.
3. Why secondary guarding cannot eliminate trapping hazards
Many contact-based systems depend on a particular sensor being activated. If an operator is trapped at the side of the platform or against a different structure without triggering the sensor, the protection may not respond as expected.
Other limitations include a body position outside the detection area, injury occurring before activation, or multiple obstacles making stopping or reversing insufficient.
IPAF has warned that no single secondary-guarding system addresses every known entrapment scenario. These devices are additional risk controls, not substitutes for machine selection, task planning, operator competence, supervision and a suitable rescue plan. See IPAF’s technical position.
A lift with secondary guarding does not therefore gain permission to work carelessly in tighter spaces.
4. What should a buyer confirm?
| Item | Question for the supplier |
|---|---|
| System identity | Manufacturer, exact version and whether it is included on the offered machine |
| Trigger method | Contact sensor, cable, non-contact detection or another method |
| Detection area | What contact positions and conditions are covered? |
| Activation response | Which movements stop? Is any reversal provided? What warnings activate? |
| Recovery | How are controls restored under the manufacturer’s procedure, and what can ground personnel do? |
| Installation basis | Factory option or later retrofit; approval and verification for this model |
A supplier question could read:
See the guide to MEWP attachments and modifications for the relevant checks.
For work close to structures, the platform’s working envelope and actual movement path still have to be evaluated independently.
Secondary guarding offers an additional way to control some trapping risks. It does not replace the first task: keeping the operator out of a trapping situation.