weighty force

Discussion in 'Engineers' Talk' started by Shake, Jul 7, 2005.

  1. Shake

    Shake New Member

    I am a lorry driver and at work we have to move pallets of goods that weigh over 1 tonne. Some people find this difficult.

    The manager has stated that it requires 29 kilograms to move a 1 tonne pallet on a level surface so should not present a problem to the average person.

    What is confusing me is that I thought that a force was needed to move an object and 29 kilograms is just a weight.

    Could some kind engineer explain this to me.


    Where
     
  2. Shake

    Shake New Member

    Sorry should have said we use a hand pallet truck (aka pump truck)
     
  3. Hi Shake, what you have to imagine is your pallet truck on the bed of your lorry with a rope attached to the handle. This rope passes over a pulley at the end of the lorry and dangles down towards the ground. This rope has 29 kilograms fixed to it. This should be enough force to start the pallet truck moving. Force is usually expressed in Newtons. Mass is usually expressed in kilograms. One Kilogram is roughly equal to 10 Newtons at sea level, but gets progressively smaller as you gain altitude. Back in the real world, common sense says that shifting a tonne of stuff by hand by yourself would be hard work. What about stopping it at the bottom of the slope, just before it crushes you up against the wall?
     
  4. Tangoman

    Tangoman Well-Known Member

    Bit of a daft statement by your manager.

    The force required to move it is going to be dependant on the friction between the pallet and the surface it is on. ALthough this is related to it's weight, the nature of the surface, and the surface area of the base of the pallet is going to be just as important.

    So a pallet with 6 3" wide planks on the bottom would be much harder to move than one with just 3 3" wide planks.

    Furthermore I would imagine the problem relates to the ergnomics of the situation.
    For example: It is far easier to lift a 40kg set of weights in the gymn, than it is to lift a 40kg sofa, the sofa is far more awkward and you are physically unable to apply your muscles in the most efficient way.

    The same probably applies here - being able to lift 29kg is not the same as being able to apply that force in a horizontal direction. For a start you cannot bring your strongest muscles in your legs into play.

    Tangoman
     
  5. Tangoman

    Tangoman Well-Known Member

    Oops - scratch that about surface area. The force is related only to the weight and the nature of the two interacting surfaces.

    Tangoman
     
  6. Mr. Handyandy

    Mr. Handyandy Screwfix Select

    AND it's on a trolley jack!!!!

    Don't think manager was quoting from book, merely saying that if you weigh less than 29kg, you are gonna have more difficulty in moving it.


    With your 29kg weight leaning back and the grip of your feet being important, you will do a better job than a 3stone(or the equivalent in kg) weakling, in a nutshell.
    (don't hear that phrase, do you - 24kg weakling ?)

    Interesting though, that you could move that if you only weighed 29kg.



    Mr. Handyandy - really
     
  7. Hitch.

    Hitch. New Member

    The size of the wheels will also make it either harder or easier..
    If its that hard, maybe they should get one of those electric pallet trucks??
     
  8. Shake

    Shake New Member

    The size of the wheels will also make it either
    harder or easier..
    If its that hard, maybe they should get one of those
    electric pallet trucks??

    The problem with an electric truck is actually getting it on the back of the wagon. When unloading pallets the forklift truck driver takes off the back 2 pallets. Then you need to work in that created space to turn the second row. An electric truck would not fit.

    Anyhow I work for a big supermarket and can assure you that even in situations were it would be feasible to use an electric truck they are too tight fisted to buy one.
     
  9. Hitch.

    Hitch. New Member

    Good point Shake! I didnt think of that!
    Looks like youll all have to struggle on!
    Anyways, a pallet truck with only 1 ton on is nuffin!
     
  10. nigel

    nigel Guest

    Ask you local health and safety officer visit and access, that should concentrate you managers mind.
     
  11. Charlie Far!ey

    Charlie Far!ey New Member

    The weight and the force are almost one and the same. the pallet weighs 10 lbs and will always weigh 10 lbs but it has a force acting on it of 9.8m/s/s2 (gravity). The force downward is exactly what you see 10lbs being acted on by a pushing force (on to a scale that has been calibrated to read back to us 10 lbs) take it to the moon and that 'pushing' force is removed and will fall as fast as a feather and reach the ground at the same time (if dropped at the same time) but it will still weigh 10lbs.

    To move a weight of n pounds the force required must exceed n pounds under the strict consideration of friction. A single man can move large boats single handed but first he has to exceed the force retaining the boat in a minimum friction situation.

    Wheels reduce the area of friction as only a small proportion of the downward force is sat on the ground hence the amount of friction is minimalised and can quite easily be exceeded. Take off the wheels and then try.

    Simple isnt it?
     
  12. Mr. Handyandy

    Mr. Handyandy Screwfix Select

    The weight and the force are almost one and the same.
    the pallet weighs 10 lbs and will always weigh 10
    0 lbs but it has a force acting on it of 9.8m/s/s2
    (gravity). The force downward is exactly what you
    see 10lbs being acted on by a pushing force (on to a
    scale that has been calibrated to read back to us 10
    lbs) take it to the moon and that 'pushing' force is
    removed and will fall as fast as a feather and reach
    the ground at the same time (if dropped at the same
    time) but it will still weigh 10lbs.

    To move a weight of n pounds the force required must
    exceed n pounds under the strict consideration of
    friction. A single man can move large boats single
    handed but first he has to exceed the force retaining
    the boat in a minimum friction situation.

    Wheels reduce the area of friction as only a small
    proportion of the downward force is sat on the ground
    hence the amount of friction is minimalised and can
    quite easily be exceeded.
    Take off the wheels and
    then try.

    Simple isnt it?



    Too simple apparently. For you.

    It is not the smaller area of friction that makes it easier to move.

    It is the fact that the wheels are on bearings and roll easily.

    Try moving it with brakes on the wheels, dippystink.

    The larger area at the meeting of the ground will make it easier to move, as the weight(downforce) it spread out over the larger area.

    With the wheels(and the bearings) this makes a mockery of any downforce calculations as different wheel configurations will change the complete set-up.




    Think about it.




    Mr. Handyandy - really
     
  13. Shake

    Shake New Member

    at the same time (if dropped at the same time) but it
    will still weigh 10lbs.


    I think Well Shtink that you are getting weight and mass mixed up.

    A mass of a body on earth and on the moon is the same but the weight of the body on the moon will be lower due to the moon having only 1/6th of the gravitational pull of the earth. Weight is gravity dependent mass is not.

    Anyway I have now convinced the powers at work that loading 24 or 26 pallets this way has risks and they have agreed to use a curtainsider.
     
  14. Shake

    Shake New Member

    Nigel

    I don't know if you are part of HSE but I did try them via their website and got a weak reply.

    Their reply answered none of the points raised.

    I asked again, stating that I was not happy with the first reply and gave my reasons, The next reply was exactly the same as the first.

    I gave up.

    The HSE stinks. They waste our money and do very little in return. They will not give you a direct sensible answer.

    If anyone at HSE wants to differ then post a general office number and I will show that some big multinationals do not give one hoot about health and safety.

    But as we all know there will be no reply from HSE as they

    a) Could not care less

    b) some other reason.
     
  15. Charlie Far!ey

    Charlie Far!ey New Member

    I understand the subject thoroughly and I have no reason to suggest that you dont either but try to explain it to someone who does not understand it.

    We will then try to explain it to this guy why mass is really weight and why weight is mass and force is there too

    Then Mr Handjob sticks in his two pennyworth which in todays terms is as the person.........nothing. The candidate is now as confused as the Blackspur Boys

    Knowing it and expalaining it are two different zones which overlap but not by much.
     
  16. Jason123

    Jason123 New Member

    Your manager sounds oh so typical these days. I attended a confined space course some years back and a 'manager' was asking what is the smallest size pipe someone can refuse to enter. The story was that a 27St gent couldnt physically enter the 2ft dia pipe, the manager wanted him disciplined for refusing to work.

    Back to your pallet problem. A tonne is a very large mass to transport. I would think the 29Kg is the minimum required to raise the tonne on the pump truck, pulling it anywhere is completely different.
    Gradients, co-ef friction etc all take there part. I would defy anyone to drag this pallet up a steep hill any distance. These trucks dont have brakes either, which is another issue again. Jas
     
  17. Rumble

    Rumble New Member

    The ability to move your pallet horizontally depends on the amount of force you can exert on the handle horizontally. A heavier person can exert more force horizontally as a by product of them having more inertia and more friction where their feet meets the floor.

    A lighter person will finde themselves moving towarrds the truck before the truck moves towards them.

    The pallet is on wheels and can be moved by a very small force - the force accellerates the truck to a speed, then a small force is needed to keep it moving at a constant speed, then another decellerating force is needed to slow it down again until it stops.

    Often there is an intial minimum force that is required to overcome real-life objects being stuck still. This initial minimum force doesn't exist in some theoretical models!

    To improve your pallet-moving ability try having the pallet truck maintained - specifically the bearings on the wheels. Any uneveness on the floor will seriously inhibit movement, that includes very small amounts of dirt - try sweeping the truck before loading.

    Anything that improves your traction - that stops your feet slipping on the floor - will be helpful. Use a degreaser on your work shoe soles.

    It's possible some knee-bending tequniques may improve matters.

    All this points to there being more in the calculation than just your body weight.

    Hope this is helpful.
     

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice