parking in 1st gear

[JHardwick]

Let's not misuse the word "roll" for "creep".

 

[PC12Driver]

Roll, creep, move, whatever. The truck won't stay where you want it to if it's parked on an incline if you assume 1st or reverse is the same as Park. And once it bumps past the compression stroke it was sitting on, then you're dealing with inertia too. That'll easily turn "creep" into "roll. "

 

[cojhl2]

There is no reason for a truck NOT to roll if it is left in gear w/o the parking brake set.



If the transmission was out of the truck, you could put it in first and spin it via the output shaft. It's just a couple of shafts and straight gears - there's nothing to lock it in place.



We know we can hand turn these engines over fairly easily with a barring tool, or even with the nut on the alternator. So there's nothing locking the engine in place either when it's off. Maybe an occasional bump of compression, but that leaks by fairly quickly (gas or diesel, every engine WILL leak down).



So there's nothing magical that will lock and hold your truck in place if you park it in first. You're just working against friction and a bit of compression that will leak down. Granted, first gear gives that friction and compression a huge mechanical advantage, but with 7k lbs+ of truck it's just a matter of time before it rolls.

Right on!!!

 

[JHardwick]

Roll, creep, move, whatever. The truck won't stay where you want it to if it's parked on an incline if you assume 1st or reverse is the same as Park. And once it bumps past the compression stroke it was sitting on, then you're dealing with inertia too. That'll easily turn "creep" into "roll. "

My truck "rolls" @ 2MPH while the engine idles @ 750RPM, it's not likely that your gonna see an 8,000# truck spin a dead engine at 750RPM. More likely the truck will "creep" from one compression stroke to the next as they bleed off.

 

[PC12Driver]

My truck "rolls" @ 2MPH while the engine idles @ 750RPM, it's not likely that your gonna see an 8,000# truck spin a dead engine at 750RPM. More likely the truck will "creep" from one compression stroke to the next as they bleed off.

I suppose that depends on the incline, doesn't it? Bottom line, regardless of the nomenclature you wish to use, it won't be where you left it when you get back.

 

[JHardwick]

I've been in the habit of using the e-brake for years, auto/manual, flat/incline, no matter. I've found that this keeps the cables from rusting and siezing to the point of having no e-brake when you really do need it.

You don't have to tell me, I use mine all the time. I was just pointing out that a truck rolling down a hill is a lot different than a truck creeping down a hill.

 

[PC12Driver]

You don't have to tell me, I use mine all the time. I was just pointing out that a truck rolling down a hill is a lot different than a truck creeping down a hill.

Isn't the end result the same?

 

[JHardwick]

Isn't the end result the same?

Not when some of these posts are sounding like a truck rolling down a hill taking out sidewalks full of people and crashing through a plate glass store front. :-laf

 

[NUKEMAN]

I can't believe this has gone on for 4 pages! I mean, c'mon, JUST USE YOUR DAMN E-BRAKE!



There, I'm done.

 

[JHardwick]

I can't believe this has gone on for 4 pages! I mean, c'mon, JUST USE YOUR DAMN E-BRAKE!



There, I'm done.

Is that your final answer?

 

[cojhl2]

I can't believe this has gone on for 4 pages! I mean, c'mon, JUST USE YOUR DAMN E-BRAKE!



There, I'm done.

I think there is a lot more to a thread like this than the final answer, that is use the parking brake.



There is knowledge always hidden in the responses. One of the things learned here is that the engine does not hold anything on compression. It is all friction!!



I kinda enjoy these threads cause there is always some ray of additional knowledge is a post somewhere.



BTW,, are the parking brakes in the new vehicles worth a darn holding backwards? The did not usedd to be for sure!!



(not covered here but usefull knowledge anyhow)::

An engine does not slow the vehicle down running against compression. That is a misnomer. Again it is friction.



True a gas engine has some holdback but very little due to the vacuum on the indraw downstroke.

 

[BGott]

I have learned to never leave a vehicle in gear when parked. Old diesels had fuel cut- off knobs, once you had killed the truck and released the knob vehicle creep or a bump could start the truck. As a mechanic I've seen lots of people get into cars and trucks and start them and then let out the clutch, not knowing that the thing was in gear. Or seen a tech bump a solenoid to bring a timing mark to the top and have the vehicle jump.

 

[cojhl2]

I have learned to never leave a vehicle in gear when parked. Old diesels had fuel cut- off knobs, once you had killed the truck and released the knob vehicle creep or a bump could start the truck. As a mechanic I've seen lots of people get into cars and trucks and start them and then let out the clutch, not knowing that the thing was in gear. Or seen a tech bump a solenoid to bring a timing mark to the top and have the vehicle jump.

You know what,, I forgot about that!!



Even today with elec solonoids on the trucks we never leave them in gear when parked. Ya shake the handle and turn the starter!!



But the big difference is Spring Brakes.



The old days (of whcih I am a part) before spring brakes, there was only residual air in the system to hold the brakes on. So the vehicle for sure had to be parked where it would not move and be chocked also.



Thanks for the reminder BGott. .