I know this is a bit over the top but I could not come up with the best way to judge the distance between the car and my rig when positioning the car to hook up for towing. I tried using spots on the windshield and aligning them with things on the RV, but nothing is really repeatable. The best solution is to have someone drive the car while you guide them into position. Side to side is not a problem itís the depth Iím always too close or too far away. Even with a telescoping tow bar.
Iím an engineer and thought there has to be a solution to my problem and here is what I came up with. While looking through eBay at some Chinese electronic suppliers I came across an aftermarket 4 sensor DME (distance measuring equipment) backup monitor for cars. The cost was less than $15.00 shipped, so I though why not.
I install the unit into my Roadmaster rock shield. I made the unit fully self-contained complete with a battery so I did not need to add a power source. I used a standard 9 volt transistor radio battery. The DME unit draws approximately 230mA when powered and it only needs to be powered when you position the car so the battery should last a long time. Just be sure to power it down after positioning the car.
I cut a plate 4.5Ē x 7.0Ē out of clear plastic then mounted the display and processing unit to it. I covered the plate with foam sealing tape except where the display is mounted so it could show through. I cut a hole in the rock shield to gain access for mounting and running all the wires. I mounted a switch to the rock shield and with some Velcro I mounted the battery inside the shield. I mounted 2 of the sensors to the front of the rock shield and fished the wires and connected them to the processing unit. Then I secured the plate to the rock shield using 4 short molly type anchors.
The DME displays distance in tenths of meters and is quite accurate. I have only tested it in my garage as you can see from the pictures but I am sure it will work very well when bouncing a signal off the back of the RV. The display is visible over the top of the dash when positioning the car.
I will attempt to add some pictures.
If you found this project interesting please check out some of the other things I have posted.