Truly Understand the Pre-Trip

Discussion in 'Questions From New Drivers' started by Wasted Thyme, Sep 2, 2020.

  1. Wasted Thyme

    Wasted Thyme Road Train Member

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    Morning all. I have studied and understand what is being looked for to pass the test. But what I'd really like to understand is the mechanics behind it.
    Example: "thumping" the tires. Exactly how does that tell you that they are properly inflated?
     
    singlescrewshaker, alds and clausland Thank this.
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  3. clausland

    clausland Road Train Member

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    Thumping's old school, get a thumper, no, don't buy one, get a simple tire iron and thump a tire you know is properly inflated, then thump one low on air. You'll feel the difference and the sound it makes. Years ago, the man only cared that it wasn't flat, now they get anal if one is 110# and it's twin is 70#. From an O/O perspective, tires aint cheap, so to run 'em low means you'll be replacing 'em sooner...
     
  4. Snoopycda

    Snoopycda Light Load Member

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    Short answer is; It does not. If you are hitting the tires on their face and with some authority you might hear a difference between the two to alert as to their pressure variation. That is if they are the same make of tire, of course.Then you pull out the tire gauge (that you always have?) and check them.
     
  5. Judge

    Judge Road Train Member

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    You gotta hit something to remain calm, dispatcher, DMs, DBLs, shop foreman that knows nothing all get lawsuits.
    Tires do not.

    But on a more serious note, you’ll hear/feel the difference on a tire say 100lb then an 80 lb one.
    Some want you to gauge them, now just fuel at loves, get tire pass points and they gauge and add air pressure to them while you fuel.
     
  6. Biomagnum

    Biomagnum Light Load Member

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    I thump the tires as well, like Clausland said. I also look at every tire to see if the sidewalk bulge looks the same. If they are not, I check the pressure. I check again after I hook up a trailer.
    Checking the tires at every stop goes a long way to keep from having problems. Check them for heat especially.
    You can also spot a low tire on a trailer by checking them before you hook up if the trailer has auto-inflation.
     
  7. singlescrewshaker

    singlescrewshaker Road Train Member

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    To pass the pre trip, in FL CDL A exam anyway, you have to state out loud to the inspector. "I'm checking the tires pressure with a guage for proper inflation." At least that's how mine went anyway..

    Thumping is what I do every time I stop for a load check during the day, for the night, & when I take off after my 10. I thump with my bare fist. Drive & trailer. Look at steers for sidewall bulge. If a tire is low, I will find it like this. The vibration in my bones, & sound is what I'm looking/listening for. Sometimes on uneven ground I hear the "thud" slightly off. Pull forward or back a few feet & try again. Also looking for shrapnel in the tire if the "thud" is off. Off a 2nd time, no shrapnel found, the guage comes out..

    I also run the same equipment day in, day out so it may not work as well for trailer swaps..
     
  8. Wasted Thyme

    Wasted Thyme Road Train Member

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    Ty all. Great info. But I think I hampered my own question with my example. I really mean all of the mechanics. Minus the electronic stuff. Not the "pass the test" answers. But the what should I really be looking for on the TT.
     
    singlescrewshaker Thanks this.
  9. Cat sdp

    Cat sdp . .

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    Always look under it for puddles every time you get out........tires too.

    Lug nuts , wheels every day. Oil level every day/ coolant is easy just look in the jug while Hood is up.

    And listen for air leaks when ever you park and it’s quiet.......

    It’s a little different when you’ve had the same truck / trailer for 10 years and your the only one who drives it.......

    I’d probably fail the pretrip test at the dmv.....
     
  10. Hazmat Cat

    Hazmat Cat Medium Load Member

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    Question wasn’t properly pre tripped so all responses are just people talking about thumping.
     
  11. singlescrewshaker

    singlescrewshaker Road Train Member

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    What I personally really do everyday might be considered overkill, but I drive a 28 year old truck..

    So other than tires we spoke of..

    -Gloves on hood up
    -Scanning for leaks or anything out of place.
    -Pull the puke tank cap & look at coolant level as mine is steel & not see through plastic like new trucks. .
    -Yank on the tie rods, drag link, pitman arm, steering shaft looking for play in the bushings
    -Scan the drums for oil, no cracks & shoes look good
    -scan the leaf pack, u bolts, hangers, & frame for cracks
    -check tension of fan & alt/ac belt. No auto tensioner so they need manually tighten time to time.
    -check oil level
    -start truck, flip on lights & 4 ways
    -walk around front checking lights, & latch hood shut
    -start down the ditch side now looking for exhaust leaks & at the frame for cracks
    -look at air lines for any spot they can "chafe" That's a favorite write up
    -check over rear suspension, tires, brakes, 5th wheel mount
    -down trailer for lights, frame, load still secure, listening for air leaks
    -trailer tires, brakes, suspension
    -go around back all lights are working, no lenses cracked
    -repeat trailer inspection road side up to the 5th wheel
    -ISO pigtail, & gladhands secure
    -check apron for cracks, 5th jaw is locked around kingpin
    -5th wheel pedestal no cracks, tires, brakes, air bags, suspension
    -drain air tanks, check road side exhaust
    -pull forward few ft & pull the johnson bar to check trailer brakes
    -stomp foot brake hard 2 times & hold few seconds to make sure no air leaks under hard brake
    -Roll out

    Might have missed something, hard to write up & keep my thoughts together. But that's the jist of what I do. If it looks like rain in the AM, I do this when I stop for the night. Then just check lights, tires, load secured, no puddle under the truck, 5th jaws..
     
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