Why Bigger Isn’t Always Better — How We Increased Throughput by Slowing Down the Grab Crane

When plant management teams face feed bottlenecks or throughput shortfalls, the instinctive response is often the same:

“We need bigger equipment.”

But in reality, bigger is not always better — and sometimes the best path to higher throughput is to run the system more intelligently, not harder.

At BIA Engineering Ltd, we recently helped one energy-from-waste plant dramatically improve grab crane performance and plant throughput — not by installing a bigger grab, but by understanding the true root causes of performance limitations.

The Situation

The plant was struggling to maintain consistent feed rates to the furnace.

Management believed the solution was to purchase a larger grab — increasing capacity from approximately 6–7 tonnes per cycle to 9 tonnes.

We intervened early and advised strongly against this approach.

Our analysis showed:

• The crane was already carrying sufficient mass per grab

• Throughput limitations were caused by how the crane was operating, not its capacity

• The OEM’s setup and control sequencing were contributing to frequent trips, positioning errors, and maintenance strain

Adding a larger, heavier grab would have:

• Increased wear and stress on crane components

• Aggravated existing reliability issues

• Likely reduced, not improved, actual net throughput

Our Recommendation

We recommended a controlled trial:

• Reduce overall crane operating speed by 40% in all directions — including hoist and grab movements

• Monitor system behaviour and plant performance during a one-month test period

As expected, this recommendation faced resistance — slowing down the crane seemed counter-intuitive when the goal was to increase throughput.

But the client agreed to the trial.

The Outcome

The results were clear and compelling:

• Crane trips and positioning errors were eliminated

• Encoder failures stopped occurring

• Hoist cable stress was significantly reduced

• The crane operated more smoothly and predictably

• Overall plant throughput increased, despite slower individual crane movements

• The system became so reliable that when one crane was out of service for maintenance, plant operations remained stable — dramatically reducing pressure on maintenance and operations teams

Why It Worked

The original problem was not the grab size — it was system dynamics:

• At high speeds, the crane was unstable and prone to faults

• Frequent trips and resets were causing lost time and operational disruption

• By slowing the system, movements became controlled and repeatable

• The plant gained more net throughput because the crane simply worked — reliably and consistently

Key Lesson

Bigger, faster equipment is not always the answer.

Understanding the system as a whole is the key to sustainable plant performance.

At BIA Engineering Ltd, this is exactly how we approach every reliability challenge:

• We challenge assumptions

• We analyse systems holistically

• We propose solutions that deliver results — not complexity

Engineering solutions beyond expectations means knowing when less is more — and helping our clients achieve better outcomes through smarter engineering.

If your plant is facing feed system or crane reliability issues — we can help you think beyond the obvious, and deliver results that last.