Exam Review & Practice

The legal foundation for the 4G restriction is MGL c. 146, sections 53 through 54A, with administrative details in 230 CMR 6.00. The agency that issues the license is the Division of Occupational Licensure (DOL), Office of Public Safety and Inspections (OPSI) — not the Department of Public Safety, which is a common wrong answer. Know the difference.

The numbers: age 18 minimum, $75 per restriction nonrefundable, 2-year term, renew within 60 days of expiration, and continuing education required at renewal under 230 CMR 6.04. The 4G is one of three restrictions in the HEML alongside 1C and 2B — a municipal-limited grouping, not general-industry hoisting. Scope is equally important: the 4G covers side-boom mowers with flail or rotary heads only. It does not authorize forklifts, aerial lifts, or any other hoisting equipment.

A side-boom mower is a carrier — a tractor or utility vehicle — with an articulating boom that swings the cutting head away from the body and down an embankment. The boom runs off the hydraulic system; the head runs off the PTO. A certified ROPS and FOPS are required on the carrier, and the seatbelt must be worn whenever the machine is moving. A rollover at an embankment edge without those protections in place is fatal.

The cutting head is the source of the thrown-object hazard. Flail heads use chains or blades rotating at high speed; rotary heads use fixed blades. Either type can launch stones and debris at lethal velocity. Guarding and deflectors reduce the risk but cannot eliminate it — no bystander should be in the danger zone while the head is running. If someone approaches, stop the head immediately.

Roadside work adds traffic to that picture. Every mowing operation is a temporary work zone governed by MUTCD standards for lane closures and flagging. High-visibility apparel is required for all workers in the zone. Struck-by injuries from passing vehicles are a leading cause of roadside worker fatalities.

The articulating boom shifts the carrier's center of gravity outboard and downward when extended. Always position the carrier on the high side of a slope and work the boom down — never park below and reach up. Operating beyond the manufacturer's rated slope limits can overcome the ROPS before it has any chance to protect you.

For utilities, the required clearance from energized overhead lines is 10 feet, measured to the boom at full extension. Underground lines and pedestals must be located and marked before mowing starts. Striking a gas or electrical facility carries consequences no schedule can justify.

The pre-shift walk-around covers the standard checklist — fluids, hoses, brakes, seatbelt, ROPS — plus items specific to this machine: PTO operation, boom pins, cutting head condition, and deflector guarding. Any removal-from-service condition grounds the machine: hydraulic leaks, inoperable brakes or steering, a compromised ROPS, a non-functional seatbelt, or structural damage to the boom. Tag it out of service and report it to your supervisor.

For the exam, read each question fully before choosing an answer. Wrong answers are usually wrong for a specific reason — a detail that is almost right but off in one key way. Eliminate what you know is wrong first. Watch absolute language: always and never are sometimes correct and sometimes traps. In this material, stopping the head when a person approaches is always correct, and skipping the pre-shift is never acceptable — but verify the context on anything less clear-cut.