The performance and capability of an electric tug, regardless of manufacturer, is influenced by the same core factors: the condition of the floor, the type of wheels on the load, and any gradients in the environment. These elements impact traction, rolling resistance, and overall performance. It’s fundamental to the physics of moving heavy loads and why a detailed evaluation of each application is essential.
Instead of purely quoting headline capacities based on ideal conditions or simply providing off-the-shelf solutions, we evaluate each application in detail before making a recommendation. This ensures the solution you receive is not only capable on paper but proven to work in your real environment, with your surfaces, and with your load configuration.
This approach is deliberate, and it ensures reliability. It’s why organisations across aerospace, automotive, pharmaceutical and industrial manufacturing choose MasterMover when performance can't be compromised.
Before looking at the variables that affect electric tug performance, it’s useful to understand the simple physics behind moving a wheeled load.
Imagine a supermarket trolley filled with ten one-litre bottles of lemonade. Even before you push it, you feel the weight settle through the wheels into the floor. Getting it moving requires deliberate effort - that’s the initial resistance.
On a smooth, flat supermarket floor, the trolley behaves exactly as you expect once it’s rolling, it stays rolling with minimal effort.
Change the environment, and everything else changes with it.
Push the same trolley across cracked or uneven ground and every bump increases resistance. You need noticeably more effort to keep it moving and maintain control. It’s the same principle with electric tugs. Poor floor conditions directly increase the force required.
Add a slope and the physics become even clearer:
Uphill: you work against gravity, needing far more force.
Stopping and restarting: the trolley settles back, so you must overcome even more resistance.
Downhill: you’re no longer pushing; you’re trying to restrain and brake the load.
The key point is simple: the trolley hasn’t changed, but the conditions around it have. Those changing conditions dictate how much force is required and electric tugs are governed by the exact same physics.
This is known as rolling resistance – the force that ‘resists’ movement when a wheeled load travels across a surface. Rolling resistance is typically expressed as a percentage of total load weight.
That percentage varies more than most people expect. Based on MasterMover's application data, polyurethane castors on smooth concrete floors typically have a rolling resistance of between 4.5-4.8%, rough or cracked concrete sits higher - between 5% and 7% depending on castor type, while metal grating is the most demanding common surface, with resistance figures reaching 8.5-10%. For a 5,000kg load, the difference between a smooth epoxy resin floor and a metal grating surface can represent hundreds of kilograms of additional force. Some surface and castor combinations fall outside standard reference figures entirely and require a bespoke calculation, which is why MasterMover assesses every application individually rather than relying on generalised data like other suppliers.
Smooth, level floors offer predictable traction and minimal resistance.
Uneven or damaged floors introduce constant variations in resistance that the tug must continually overcome.
Rough outdoor surfaces, expansion joints or cracked concrete amplify rolling resistance, especially under heavy loads.
Contaminants like dust, oil or debris can reduce traction.
For light loads, the impact of these variables can be subtle, but for industrial loads weighing several tonnes, they become critical.
Tip: When working with any electric tug supplier, make sure to share details, photos and information on the worst part of the route you need the equipment to move over. This ensures any electric tug is correctly specified to cope with the worst-case conditions.
MasterMover: Our comprehensive range of electric tugs can move loads from as little as 500kg right up to 300,000kg. We have specific solutions available for working on poor floor conditions and challenging environments (e.g. outside, rough/cracked concrete, grating, rails etc.)
Castor wheel type, condition and configuration influence how much force is required to move a load. Worn, misaligned or incorrectly specified castors can increase rolling resistance significantly, making the tug work harder and steering less predictable, regardless of how capable the machine is on paper.
Key factors include:
Wheel diameter (larger wheels roll more easily)
Wheel material (softer materials can deform under load, leading to higher rolling resistance)
Number of wheels (more wheels can increase drag/rolling resistance)
Castor alignment and condition (poor castors significantly increase initial force)
Load distribution across the wheels
Tip: On new trolleys, work with a reputable castor supplier to assess your environment to ensure any castor wheels are correctly specified for your requirements. If you have existing trolleys and equipment, make sure to provide clear photographs and specifications of your trolley’s castor wheels and any reputable electric tug manufacturer will assess this.
MasterMover: Our Product Specialists evaluate every application, with a particular focus on castor wheels and the impact this has on rolling resistance.
Even a small incline fundamentally changes what an electric tug must do. On a slope, an electric tug is no longer just moving a load, it's stopping it, holding it, restarting it, and controlling it.
Gradient has a significant impact on what any electric tug can safely move, regardless of manufacturer. As slope angle increases, the effective load capacity reduces, and that reduction compounds further when rolling resistance is factored in.
A machine rated to move a given load on a flat floor will have a meaningfully lower capacity on a gradient, which is why gradient data should always be assessed as part of the specification process. MasterMover publishes slope performance data for every machine in the range and calculates performance at the worst-case point on your route before recommending a solution.
On an incline, the tug must work against gravity to prevent the load rolling back. Restarting on a slope requires more traction and power than starting on a level surface. Travelling downhill requires the tug to restrain the load, requiring additional force.
Tip: If you're unsure of the gradient your load needs to travel up or down, it's easy to check. Many free mobile apps can measure slope or incline. Simply place your phone on the steepest part of the route and record the angle. Sharing this with your electric tug provider ensures they can specify the correct solution.
Bonus tip: Slopes have a direct impact on safety. Any supplier you work with should ask for this information and carry out the correct calculations. An incorrectly specified tug on a gradient can create real risk for both operators and equipment.
MasterMover: When assessing any application involving slopes, we calculate forces at the worst-case point, when the load must stop and restart on the steepest section. Before recommending any solution, we confirm:
The maximum gradient on the full route
The force required to stop, hold and restart at that point
That the specified machine can deliver that force safely and consistently
Summary: Slopes magnify the force requirements and introduce critical safety considerations. Proper measurement and calculation ensure the tug can stop, hold, and restart safely on inclines.
The heavier the load, the more significant every variable becomes. A slight increase in rolling resistance for a light trolley is manageable. The same increase under a heavy industrial load can push the forces involved beyond the safe working capability of a tug.
The total load weight is unsurprisingly a critical variable when it comes to specifying a suitable load moving solution.
Tip: When calculating the total weight of the load, make sure to factor in the weight of the trolley. For example: Load weight = ~4,650kg + trolley weight = 1,200kg. Total weight = 5,850kg.
MasterMover: With a range capable of moving loads over 300,000kg, we’re no strangers to heavy weight movements. We’ll work with you to fully understand your application, ensuring any solution is specified to deliver in real-world applications.
Weight alone doesn’t determine capability - its interaction with floors, castors and gradients does, and as loads get heavier, every resistance variable is amplified.
Each application is reviewed by our Product Specialists to understand the load, the route and the environment in full. This engineering-led approach ensures that our equipment delivers reliable, consistent performance for customers across some of the most demanding industrial settings.
Our team will always review:
• The full route
• Floor condition
• Wheel types, configuration and condition
• Gradient angles
• Usage rates
• Coupling points
• Turning points and required positioning
• Specific environmental requirements (i.e. Stainless Steel, ATEX)
From this, we calculate the realistic required output of the tug for your application. This allows us to correctly specify a machine based on the application variables, not just a perfect-world maximum capacity.
As we’ve discussed in this blog, generic capacity ratings are based on perfect conditions: flat floors, excellent wheels and clean, consistent surfaces. Real environments vary.
If you’re looking to buy or evaluate electric tugs, whichever supplier you choose make sure:
They gather and review information about your application
If they can, they visit site. If they can’t, they ask for photos of your environment and load
They don’t just specify a solution based solely on load weight
MasterMover’s approach ensures that the tug you receive is specified based on the actual conditions of your application so that:
The tug performs reliably across the full route
Operators can work confidently with predictable control
Surfaces, slopes and castors are accounted for
Load movement stays safe in every scenario
An aerostructure manufacturer used a competitor’s tug rated to move 20,000kg to unload a large autoclave. On paper, it looked more than capable.
In reality, it could push the load into the autoclave, but it couldn’t pull the load back out. The tug didn’t have the traction or power to handle the pull forces required. This meant that when operators came to unload the autoclave, the machine kicked back, risking potential damage to highly sensitive aerostructures and required operators to use brute force to move the load – risking injury.
We carried out an engineering assessment, covering:
All application data (rail conditions, max load weight, movement requirements, floor conditions, coupling point etc.)
Worst case calculations on rolling resistance inside the autoclave chamber
The data confirmed the issue:
The push force required exceeded what the “20,000kg capacity” tug could safely deliver.
The supplier’s headline rating didn’t reflect the real forces in the application.
Solution: We specified the MasterMover MT600+, providing the required pushing power and controlled traction.
Impact: The MT600+ replaced an underpowered competitor machine that was kicking back when moving the load, creating a genuine risk of operator injury and potential damage to the aerostructure composites being handled. With the correct specification in place, both risks were eliminated. The movement became a controlled single-operator process.
To guarantee the correct machine is selected, suppliers should review:
Photos or videos of your full route
Details of the worst floor conditions
Castor wheel size, material, alignment and condition
Total load weight plus trolley weight
Slope or incline measurements
Usage frequency, duty cycle and stopping points
Accurate specification relies on understanding real application conditions—not just the load weight.
Headline capacities are measured under ideal test conditions: flawless floors, excellent castors, zero gradients and minimal resistance. In real environments, rolling resistance, uneven surfaces, worn wheels or contaminants can reduce usable capacity. Actual performance must be calculated based on your specific route and conditions.
The maximum gradient that an electric tug can handle varies significantly across different suppliers. Each model in MasterMover’s range has specific slope capabilities. The SM100+, for example, has a maximum slope clearance of 30°, but that figure represents the steepest gradient the machine can operate on.
What the slope rating alone doesn't tell you is how load capacity changes as gradient increases. As a slope steepens, the maximum load a tug can safely move, stop and restart decreases, and that reduction is compounded further by other application factors such as floor condition and castor wheels.
MasterMover publishes slope performance data for each product and calculates the forces involved at the worst-case point on your specific route before recommending any solution. If your application involves a slope, share the gradient measurement with our team.
Yes. Outdoor routes introduce higher rolling resistance and more traction variability due to rough concrete, grating, rails, debris and weather conditions. A tug must always be specified for the most challenging part of the route to ensure safe and consistent performance.
Drawbar pull is the engineering term for the force an electric tug can exert to move a load. MasterMover specifies this as push/pull force - the maximum pushing or pulling power the drive system delivers at the point of connection to the load, typically measured in Newtons or kilogram-force.
It is one of the most important figures in any specification, yet it rarely appears in standard product comparisons. The reason it matters is that push/pull force determines whether a tug can move your load in your environment.
MasterMover provides push/pull force data for every machine in the range. When evaluating any electric tug, ask the supplier to demonstrate how that figure was calculated against your specific conditions.
Wheel diameter, material hardness, bearing quality and alignment all impact how much force is required to move a load. Even a single worn, damaged or misaligned castor can increase resistance drastically, making steering more difficult and demanding more power from the tug.
A mis-specified tug can introduce significant risks, including:
Loss of traction on slopes
Inability to stop or hold the load
Excessive operator effort or unexpected load behaviour
Mechanical strain
Uncontrolled movement on uneven surfaces
Correct specification ensures the tug can safely stop, hold, control and restart the load in the most challenging conditions on your route. At MasterMover, that’s why we carefully vet every application. As the market-leader in electric tug solutions, we’re here to provide you with a solution that works from day-one – on every bit of your application.