You are correct, there is limited space on all sides of the cabinet, as well as the top and the bottom.

How about a slot in (or attached to) the moving car, for the switch to pass through, that ends in time to shut it off at the right moment?

 

This old dra wer opener may not match your system, but what we want is a lead common only to down, like lead
from motor + to lower relay contact, toward ground. Insert 1 or more diodes rated for motor current in this lead. About .7 V drop / diode.
Just drop thumbnail any old place?

 

Thanks all for the advice. After careful consideration and all the advice, I opted to extend the piece of metal that presses against the lever switch. With a 6" piece, I was able to consistently trigger the switch and not go past it. Thanks!!!

 

I do not think we have seen a schematic, of the current motor control.

But what about using the make contact in the lower micro switch, to actively brake the motor?

It's the same way most wiper motors use to park the wipers at the bottom of the wind shield.

 

Bit late in the game now, but in hindsight it might have been wiser to use the two-speed 3 brush wiper motor.
Max.

 

Adding suppression diodes across the relay contacts should greatly damp the overrun of the motor when the power is removed.
You should have those diodes anyway to protect the relay contacts from the motor inductive spike.
If you post a diagram of your connections I can tell you where to put them.

 

I recommend using PWM to drive the motor when lowering.

 

Try using a smaller spool drum it will slow down the travel and lower the holding torque. Another trick though more complicated adding a timing relay to momentary reverse the polarity acting as a brake.

 

Gravity will tend to extend the coast time of the motor in the down direction. Looks like you could use dynamic braking. The thread here... http://forum.allaboutcircuits.com/threads/12v-go-cart-forward-reverse-switch.94178/#post-693690 talks about controlling a go-cart, but the theory is the same. Post 13 talks about dynamic braking and post 15 give a link that includes a very well used circuit that has, as a side benefit, dynamic braking.

As a mechanical solution, could you install a positive stop that would engage just beyond the point that your down limit is actuated?