Loading the lesson
Loading the lesson
Search AllRounder.ai
Search the courses, subjects, tracks, games and features, or jump straight to a page.
Search the courses, subjects, tracks, games and features, or jump straight to a page.
Learn it your way
A short class with Sarah and her students. The other ways are under More.
Sign up free to listen. Transcripts are free to read.
Let's start with rolling resistance. Can someone tell me why we convert vehicle weight into tons?
Isn't it because rolling resistance is given in kg per ton?
Exactly! For our example, a 50,000 kg vehicle converts to 50 tons. If rolling resistance is 28 kg per ton, what do we get?
We multiply 50 tons by 28, which gives us 1400 kg of rolling resistance.
Great! So, if we need to know the total resistance, we also have to consider grade resistance. Let’s take a look at that next!
Now, moving on to grade resistance. When machines climb a slope, what do we need to account for?
The slope's steepness and how it affects the force opposing the vehicle!
Exactly! If a slope is 4%, that means for every 100 meters horizontally, the vehicle rises 4 meters. How do we calculate the tractive effort needed for this grade?
We take the percentage and multiply it by 10 kg per ton. So for a 4% slope and 50 tons, it should be 4 times 10 times 50?
That's right! So that’s 600 kg for grade resistance. What’s next?
Excellent! Now let's find the total resistance. How do we combine rolling and grade resistance?
We just add them up! So, 1400 kg plus 600 kg gives us 2000 kg total resistance.
Almost there, but remember there were some earlier numbers in our example. Correct this with rolling resistance being 900 kg for another case.
So that makes the total resistance 1500 kg.
Perfect! And this indicates the minimum tractive effort needed for a project site. What machine should we select based on that?
Now that we know total resistance, how do we utilize that in selecting equipment?
We need to know the maximum rimpull of the machine.
Exactly! If the maximum available rimpull is 7000 kg, how much power do we have left for actual work after overcoming resistance?
If we use 1500 kg to overcome resistance, we have 5500 kg for towing!
Correct! So remembering this power-pull relationship assists in ensuring we choose the right machine for the task. Keep these calculations in mind!
The resistance encountered due to a vehicle's weight and the surface.
The additional resistance faced when moving up a slope, depending on its steepness.
The force required to counteract both rolling and grade resistance.
The usable pulling power of a vehicle, calculated after deducting resistance forces.
For a machine with a gross weight of 50 tons on a road with a rolling resistance of 28 kg per ton, the total rolling resistance would be calculated as 50 tons * 28 kg/ton = 1400 kg.
When calculating grade resistance for a 4% slope, apply the formula for tractive effort needed: 4% * 10 kg/ton * 50 tons = 600 kg.
To climb a hill, your power must rise, for every slope, see ‘Resistance’ in size.
Once upon a time, a truck wanted to climb a steep hill. He had to prepare carefully, measuring his load and the hill's height to ensure he had enough power to overcome the challenges ahead.
Remember R-G-T: Resistance, Grade, Tractive, to conquer your vehicle’s uphill grape!
RAGE: Rolling, Assist Grade Equivalence to remember essential resistances in machines.
Term
Definition of Rolling Resistance
Click to flip
Term
How to calculate Grade Resistance
Click to flip
The force opposing the motion of a vehicle due to its weight and surface interaction.
The force opposing a vehicle's movement when ascending a slope, influenced by the slope percentage.
The force exerted by a machine to overcome resistance and move loads.
The usable tractive force generated at the point of contact between the tire and the ground.
The ratio indicating the amount of grip between the wheel and the travel surface.
This section explains how to calculate rolling and grade resistance for vehicles, helping to determine power requirements for effective machine operation.
In this section, the calculation of rolling resistance based on vehicle weight and rolling resistance per ton is discussed, followed by an explanation of grade resistance due to incline. It emphasizes understanding tractive forces required to overcome resistance while operating vehicles on slopes.
In the study of major resistances affecting vehicle performance, we focus on rolling and grade resistance. Rolling resistance is calculated by converting vehicle weight into tons and applying provided rolling resistance values. For a machine weighing 50 tons and encountering a rolling resistance of 28 kg per ton, the total rolling resistance amounts to 1400 kg. Additionally, when a vehicle operates on a slope, grade resistance arises from the gravitational force opposing its motion. This section illustrates how to quantify this force based on the slope's percentage—4% grade equates to a resistance of 40 kg per ton. Thus, we see the total resistance combining rolling and grade resistance, with their calculations leading to critical insights on necessary tractive efforts and suitable machine power selection.