Technical Specifications in an Overhead Crane RFQ: Why Duty Class and Options Decide the Next 25 Years

Most overhead crane problems we're called in to fix were baked in at the RFQ stage. The wrong duty class, a copy-pasted spec sheet from a previous project, or a missing option like a load display or key-card access — and the owner lives with the consequences for 25 years. The equipment is only as good as the technical specification that bought it.

This post is about how to write an overhead crane RFQ that actually reflects the operation, and why the "small" options are usually the ones that decide whether the crane is safe, productive and defensible. It pairs with our Overhead Crane Specification Consultant and Overhead Crane Bid Review services.

The RFQ is the contract

Whatever ends up in the technical specification is what the OEM prices, builds and hands over. Anything not in the spec is either not supplied or supplied to the OEM's default — which is almost never what the owner would have chosen. "We'll figure it out at the submittal stage" is how owners end up with Class C hoists on Class E duty, no load display on a critical-lift crane, and no access control on a shared shop floor.

A defensible RFQ specifies four things clearly: duty class, control philosophy, safety and access options, and documentation deliverables.

1. Duty class — get this wrong and nothing else matters

CMAA service class (A through F) is not a marketing tier — it's an engineered rating for the number of load cycles, average load ratio and utilization the crane will actually see. Undersizing it is the single most expensive mistake in overhead crane procurement.

• Class A / B — standby or light service. Powerhouse, maintenance-bay, light assembly.
• Class C — moderate service. Machine shops, paper-mill machine rooms.
• Class D — heavy service. Foundries doing occasional handling, fab shops, heavy machine shops.
• Class E — severe service. Cement mills, lumber, container handling, magnet or bucket service on a schedule.
• Class F — continuous severe. Steel mill hot-metal, scrap yards, continuous production handling.

The failure mode we see repeatedly: a production crane specified as Class C because "we don't lift full capacity very often." Six years later the wire rope, brakes and gearbox are chewed through, and the owner is paying to rebuild a crane that should have been Class D or E from day one. Our CMAA Crane Consultant page walks through class selection in detail.

2. Control philosophy — VFD is not optional on modern duty

Two-speed contactor control on a heavy-service crane is a legacy decision. Modern specifications should default to variable frequency drive (VFD) on hoist, trolley and bridge, with the following called out explicitly:

• Micro-speed / creep speed for spotting critical loads
• Anti-sway on long-travel bridges (particularly steel, paper and container)
• Regenerative braking on the hoist with defined line-regen or resistor duty
• Saved and delivered VFD parameter files as part of turnover documentation

Without these called out, the OEM ships their base drive package — which may not include anti-sway, may lack micro-speed resolution, and almost never comes with a copy of the parameter file the plant will need in five years when the drive fails.

3. Load display, overload and load management

A load display in the pendant or cab is one of the highest-value low-cost options on any production crane. It converts every lift into a data point — the operator knows the actual load, maintenance can trend overload events, and the safety case for critical lifts is documented rather than assumed.

Related options that belong in the spec:

• Overload limiter with logged event history (not just a cutout)
• Load summation on tandem-lift or dual-hoist cranes
• Weigh-in-motion or lift-count logging for high-cycle operations
• Load-moment / anti-two-block where geometry warrants it

On any crane above Class C, or any crane doing critical lifts, "the operator knows what it weighs" is not an acceptable control.

4. Access control — key-card, RFID and operator authorization

Shared shop floors, EPC construction sites and multi-shift operations all have the same problem: anyone with a pendant can operate the crane. That is a CSA B167 and OSHA exposure and, under the newer edition of B167, a documentation gap on operator authorization.

Modern specifications should require:

• Key-card or RFID authorization at the pendant, cab or radio transmitter
• Individual operator IDs tied to the crane's data logger
• Configurable authorization levels (operator, maintenance, inspector)
• Lock-out integration with the plant's LOTO procedure

This is not gold-plating — it's how you enforce the authorization requirement your compliance program is already committed to. Our CSA B167 Compliance Consultant page covers where these controls intersect with the standard.

5. Safety and protection options worth calling out

Options the OEM will not supply unless the spec names them:

• Anti-collision between bridges on shared runways (laser or radio)
• Zone limiting / no-fly zones around obstructions or personnel areas
• Slack-rope detection on hoists handling ladles, magnets or grabs
• Cold-weather / heated-cabinet packages for outdoor or unheated bays
• Wash-down or corrosion packages for food, chemical or coastal environments
• Redundant limit switches on critical-lift or hot-metal cranes
• Black-box / event data logger with defined data retention

Each one is inexpensive at the RFQ stage and expensive as a retrofit.

6. Documentation deliverables — the part everyone forgets

The RFQ should specify, as a contractual deliverable:

• CMAA calculations and duty-class certification
• Structural, mechanical and electrical drawings (native format, not just PDF)
• VFD parameter files, PLC program with comments, ladder logic
• Complete parts list with OEM part numbers and recommended spares
• Commissioning and load-test records
• Operator, maintenance and inspection manuals in the owner's language
• Modification and re-rate procedure

Without these listed as line-item deliverables, the OEM's default turnover package is what shows up — and it is almost never enough to maintain the crane for its service life.

Where CAG fits

We write and audit RFQ technical specifications and review OEM bids on behalf of owners, EPCMs and end-users. Because we are vendor-neutral, the spec we write matches your operation — not the OEM's preferred configuration and not a legacy document from a project ten years ago. When a bid comes in $200k below the others, we can tell you which options were quietly removed to hit that number.

If your next overhead crane RFQ is being written from a copy of the last one, that is where to start.