View Full Version : Handicap trike speed controller

Duct Taper
03-04-2010, 06:21 PM
I have a friend, Bob, who is in his mid-80's with sight and walking disabilities. He bought a new Palmer Independence handicap trike probably ten years ago and is having problems with the speed controller.

He uses this trike as his daily transportation in our small town every day of the year, rain or snow or -24 below. He has to travel up and down two hills of 100' elevation over a mile in distance, twice daily. He estimates that he has traveled over 15,000 miles. Bob is the "Iron Man" of our coffee group!

Here is the problem. The speed controller also affects the braking. When he releases the throttle the trike brake comes on full, a dangerous thing to happen coming down one of the hills in the snow.

He has done electronic repair for years and could fix the controller, but doesn't have a schematic. Can anybody direct me to where I could find a controller schematic for a Palmer Independence Model 24 handicap trike?

03-04-2010, 06:51 PM
Not sure where you'd find such a schmatic other then the service manual for that perticular trike.

You might be able to figure out what kinda motor and/or braking system it uses (it might just use the motors for brakes by locking them) and replace the controller with a compatable one thats more configureable or does what you want. Afaik theres basicly off the shelf controllers for any kinda motor you could wanna drive, if you have the cash.

Alternately if it has seperate brakes, it might just be possable and simpler to disconnect them and provide a seperate brake control, either via a new control wired into the existing brakes (if they are linear controlable) or via a new system like a disk brake + cable, like those addon systems for bicycle front wheels, or gocarts.

Before going this route id double check the motor controller does not freak out and refuse to run with the brakes disconnected however. You might need to remove the brakes but leave them attached electricly, or make a 'fake' brake (something electricaly similar enough to fool the controller into thinking they are still attached)

03-04-2010, 06:51 PM
Palmer has an 800 number you can call. I wonder if they offer that over the net.

03-04-2010, 06:59 PM
All i can find you is the information request form from palmar


all the best.markj

Duct Taper
03-05-2010, 12:44 AM
I did contact Palmer and they said to remove the controller and send it in to them. This is his only transportation so that is not practical, especially if they take a month to get it fixed. He does electronic stuff all the time and with the schematic to look at he can fix it. Palmer won't send him a schematic though.

I don't do electronics other than putting batteries into a flashlight so I can't help. :) They probably use some off-the-shelf controller that has a schematic available in some forum on the internet, it is just a matter of finding one.

The trike does have a free-wheeling switch so the electronic braking can be disabled, but the only other brake on the trike is a small front wheel drum brake. He had to rely on that once when the keyway in the rear drive axle gave out coming down the hill and it was not adequate. We may have to look into doing some lathe and milling work to adapt a disc system to the rear axle eventually.

Thanks for the ideas though.

03-05-2010, 01:03 AM
I don't know where you are based but if in the UK, try contacting REMAP or in Australia TAD. These volunteer organisations make gadgets for people with disabilities and may have had to modify one of these controllers for some reason.
For those who would like to use their workshops to do a bit of community service, I recommend it - this is the group I work with

Duct Taper
03-05-2010, 02:19 PM
That TADSA organization looks really good. I have done some of this type of work already for local folks in Southern Minnesota, USA and it is really satisfying. I just don't do electronics but Bob is expert in that. Getting the schematic is the problem.

I am trying to track down some drum brakes that can be put on the back wheels. They already have the drums cast into the wheels so it might just be a matter of finding the right diameter brake mechanism. He can put the drive in freewheeling mode and use the mechanical brakes if we can't find a schematic.
Thanks for the help.

03-05-2010, 02:32 PM
The speed controller is shorting out the motor when the throttle is released. This makes the motor act as a generator under maximum load and is a very effective brake. Insert a large power diode in series with one of the motor leads and it will disable that function. The diode will need to be rated for about 50 amps at double whatever the total battery voltage is. If some braking is desired a low value high wattage wirewound resistor can be placed across the diode to allow for some braking current to flow. The resistor will become hot.

The main disadvantage to this approach is that reverse will not work, if it has reverse. To overcome that a switch can be placed across the diode to effectively remove it from action. That way the braking function can be turned on or off.

03-05-2010, 04:24 PM
If you are in Minnestota, you might want to contact Courage Center in the Twin Cities. I know they do a lot of apative stuff for the handicaped and they might be able to help you out with a schematic. I believe they also have a web site.


Weston Bye
03-05-2010, 04:55 PM
I did contact Palmer and... Palmer won't send him a schematic though..

This doesn't suprise me. Lawsuits, etc. How about buying a second board? That way, you friend can use it as a reference to fix the first, and have a spare on hand if (when) something breaks again. 15K, lots of miles for such a device. Sounds like your friend is a pretty sharp old guy.

Duct Taper
03-05-2010, 06:35 PM
Well Bob is a sharp guy, a bit ornery but who isn't. :) He is self-educated but his son has an Electrical Engineering degree from MIT. The son can look at a circuit board and draw out a schematic but he is in Boston, only a quick 1500 miles away. And Weston, a spare board is a good idea..... IF the Palmer folks will send one out.
Thanks Evan for the by-pass idea and I will let Bob know but I think he wants to correct the problem within the controller.

The Artful Bodger
03-05-2010, 07:52 PM
Do we know if the controller is acting as designed?

Presumably one non-electronic fix for this problem would be to adjust the travel of the throttle so that it cannot get to the 'brakes applied' point.

03-05-2010, 08:05 PM
Adjusting the throttle isn't likely to work. The problem in the controller is almost certainly a shorted transistor that is responsible for modulating the braking effort any time the machine is slowing down. Because the part has failed maximum braking effort is applied the moment any effort at all is called for. Since the machine has a free wheeling mode it implies that DC braking is used anytime the throttle position is reduced.

03-05-2010, 10:09 PM
It occurs to me that the problem could be with the throttle itself, and not the controller. What means is provided to get the variable braking signal to the controller- Also you said 'release the throttle and the brakes come on fully'- I don't mean to insult anybody, but would you not gently roll the throttle back to proportionally apply the brakes? Maybe there's nothing wrong except the operator 'forgot' how it works. I've seen that lots of times with simple things, and done it myself.

If it is a throttle problem, it could be a wire off or broken inside the insulation. I'd want to carefully check out any area where the wiring gets twisted while steering, things like that.

Duct Taper
03-05-2010, 11:05 PM
The brakes come on full when the throttle is turned down even a little bit. We have not taken apart the throttle but maybe we should look at the wire issue too. Thanks.

03-06-2010, 11:22 PM
if you want to buy a new controller. Here's a place that has them.

Duct Taper
03-11-2010, 12:47 AM
Thanks to everybody who responded. After following leads here that lead to more leads I came upon a company that makes DC motor speed controllers for many purposes, Kelly Controls, LLC. Their website is www.newkellycontroller.com for their newest tech and www.kellycontroller.com for their "now-obsolete but still useful and lower priced" models. We can get a non-regenerating controller for 24V-36V with 80-200A capacity for $79 and the same thing in their regenerating version for $139.

My friend Bob will pick up one of the regenerating versions to use until he can get the original Palmer controller fixed, and then I will use it on a golf cart conversion that I am building.

I will still machine some hubs to convert the rear wheels of his Palmer trike to accept mountain bike hydraulic disc brakes as a safety feature in case any keyways blow out again. That will probably never happen again but he is really paranoid about that after coming down the 100' elevation hill without any control. Had to go change his underwear on that one!

Lew Hartswick
03-11-2010, 09:17 AM
I guess if he's 1500 from Boston he isn't too close to Albuquerque.
I've circuit traces and drawn up the schematic for many a switchmode
power supply and lots of video and deflaction boards for monitors
that I couldn't get schematics for. The drives for mill tables and other
stuff over the years also. It would be convient if folks put an aprox.
location in their posts. :-(