Maximum step height

[pasquinade]

I apologize for insisting on this topic but I’m quite interested in it. I got around to computing the actual step height that the outlander would be able to go over as discussed in this post http://www.myoutlanderphev.com/forum/viewtopic.php?f=10&t=2958&start=70. Using the following data:

Front motor torque = 137 Nm
Back motor torque = 195 Nm

Front gearbox ratio = 9.663
Back gearbox ratio = 7.065

Wheel diameter = 705mm -> radius = 352.5 mm
Weight = 2000 kg

Considering that both front wheels go over the step at once, I arrived at a step size of 9cm. Very disappointing, I confess the “small boy” in me was expecting much more (do not consider this a fault of the PHEV since other cars would be similar).

To ensure I was not completely off the mark I placed a cement block measuring 14cm in height in front of each wheel and tried to go over it by flooring the accelerator. Did not go over - no wheel slippage but not enough torque (I have a video but not very interesting .

Notice that I assumed a stiff suspension and perhaps taking the suspension into account will allow for a temporary weight redistribution with the back wheels.

Also this situation can usually be avoided by going over the step one wheel at a time. In this case I compute a step height of 19cm (not taking into account possible effects of the differential). In this case the suspension is crucial to ensure only 1/4 of the weight is lifted and not the whole front, by sagging and helping to get over the obstacle.

Hope this further contributes to better understand the capabilities of the PHEV. I did these tests last week and was hoping to have a bit of time to field test more precise heights, but it seems the rain is against me...

 

[phevnor]

Enjoy watching physics and dynamics calculations in practice. It kills any "good" discussion.
Luckily we have help from kinetic energy and often one wheel at a time to climb, so not many (non) PHEV's standing stucked along the road.

 

[SolarBoy]

Oh my word ... please do post the video, and looking forward to your further tests!

 

[ian4x4]

Very interesting.
This probably explains why wheel chocks are so efficient at stopping vehicles (and aircraft) from rolling away, even when engine testing.

By the way, won't your one wheel calculations be effected by the "weight transfer" caused by the anti-roll bar.

 

[pasquinade]

Here are the videos, but as I said, quite uninteresting.

Cement bricks on both front wheels. Back wheels were free.

https://youtu.be/QbigRucmj2Y
https://youtu.be/8l4eiiWaCSs

Any hints as how I can embed these in the forum? (I'll try to check in other posts and will re-edit this post if I get a solution) - EDIT: AH! they embed automatically!

 

[fatnat]

In a previous post last month

http://www.myoutlanderphev.com/forum/viewtopic.php?f=10&t=2964&view=unread#unread

I discussed my 4x4 beach safari where we accessed the beach via very rough limestone 10k trail with rocks impeding smooth access, the rocks negotiated were of sufficient height and variety to scratch but not dent/damage the underside carriage. The strategy used was for the wheels to climb over the top rather than the phev simply passing over the larger rocks. For your information we were was using 70 profile tires deflated to 18psi.
Anyway the first outcrop we encountered the phev did not want to climb over the rock like in your video it simply froze, once the wheel electronic stability control (ESC) was deactivated from standstill the phev slowly climbed over that rock and all subsequent rocks on the way.

So in your example was the ESC deactivated?

Further once on the beach the 4x4 instructor wanted to demonstrate to the other pupils who had the standard 4x4 Pajero's & Prado's, Hilux etc how to use the max rescue tracks once the vehicle is bogged. After reducing the PSI to 10psi I reversed the PHEV into the boggy area of the beach some 5 meters from the surf and it sunk a little into the sand. From there the instructor requested I try and pull myself out with the full expectation it would further bog itself. Once depressing the pedal further and further without any wheel spin the phev simply got out of the boggy sand with out incident. Mind you it felt as if nothing was happening during this procedure. The instructor also got in the car and we pressed all the buttons on and off but were not able to get it bogged!

We tried this 5 times with the ESC on and off and without it getting bogged, so the instructor gave up and told the group "we cant get the hybrid bogged" we will use another car. I was so proud!!

Not sure how my experience tallies up with the phev not being able to overstep a little log? Perhaps it was simply the 70 ATP profile tires with lower psi and the additional grip rather than the 55 profile tires 40 psi?