Measured Specs on 12V DC Gearmotor (Windshield Wiper Motor)

I purchased a couple of these new windshield wiper motors from ebay. They are not the common Saturn type of motor, but similar. They have
only 2 wires, and the negative is isolated from the housing (unlike the Saturn motors). I did not like the Saturn motors because of the chassis gnd. If used as a servo, the chassis would be hot in one direction.
I took some torque and current measurements using a Fluke 337 clamp meter and a 50lbs fishing scale. I made a simple jig to mount the motor solid to the bench, then attached a 12" steel tube arm to the shaft. I then attached my fishing scale exactly 12" away from the center of the shaft and mounted it solid to the bench.
I used a 12V 7.5ah sla battery fully charged to 12.6V. This battery can source 72A for < 10s, so there was plenty of current for my quick tests.
Results:
Stall Current: 45A (voltage drop to around 10V) Stall Torque: 23 ft. lbs.
No load Current: 2A (motor running)
In Rush Current: 8.3A (no load)
All results were very similar in both directions.
Unfortunately, the motors have no markings on them, but they look just like most of the motors that are sold at surplus stores for around $20.00. They have 3 - 6mm mounting bolts and run at around 60rpm no load.
I plan on using these motors for my RC land speed car project. One for the steering, and one for the hydraulic brake. After measuring them it looks like they may be a bit overkill, but it can't hurt. I'll just need to make sure I set up my servo drivers properly (end limits) and have some good mechanical stops to avoid breaking anything!
Terry
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I purchased a couple of these new windshield wiper motors from ebay. They are not the common Saturn type of motor, but similar. They have only 2 wires, and the negative is isolated from the housing (unlike the Saturn motors). I did not like the Saturn motors because of the chassis gnd. If used as a servo, the chassis would be hot in one direction.
I took some torque and current measurements using a Fluke 337 clamp meter and a 50lbs fishing scale. I made a simple jig to mount the motor solid to the bench, then attached a 12" steel tube arm to the shaft. I then attached my fishing scale exactly 12" away from the center of the shaft and mounted it solid to the bench.
I used a 12V 7.5ah sla battery fully charged to 12.6V. This battery can source 72A for < 10s, so there was plenty of current for my quick tests.
Results:
Stall Current: 45A (voltage drop to around 10V) Stall Torque: 23 ft. lbs.
No load Current: 2A (motor running)
In Rush Current: 8.3A (no load)
All results were very similar in both directions.
Unfortunately, the motors have no markings on them, but they look just like most of the motors that are sold at surplus stores for around $20.00. They have 3 - 6mm mounting bolts and run at around 60rpm no load.
I plan on using these motors for my RC land speed car project. One for the steering, and one for the hydraulic brake. After measuring them it looks like they may be a bit overkill, but it can't hurt. I'll just need to make sure I set up my servo drivers properly (end limits) and have some good mechanical stops to avoid breaking anything!
Terry
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Depends on the application, I suppose, but I don't usually like to use this type of motor because: - the main gear often gets shot if someone applies too much torque to it. - the motors draw a lot of current.
For applications in this class (inexpensive, no special operating parameters) I prefer to use cordless drill motors with the built in planetary gears.
Lots to choose from. And prices vary depending on quality.
DOC
Terry wrote:

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On Jul 13, 2:27 pm, snipped-for-privacy@sympatico.ca wrote:

Yes, I have used some of the 18V cordless drill motors for the drive system on a robot I was building a while back. I think I would still need to gear it down further to be used for steering. I could also reduce the voltage, but then I would be loosing some torque. I'll have to check them out and see how strong the ones I have are.
Ya, I am a little worried about the gears on those worm drive motors. For the brakes, I don't think it will be a problem at all.
Thanks for the input.
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Nuther point that might help...
I put together something recently where I made a small spring loaded clutch.
It was also for steering. In my case a tricycle. And I needed to build an aditional gear box as well.
Takes a little bit of machining and you need to get the spring pressure about right for the job.
But you avoid the limit switches problem.
DOC
Buy my junk! http://www3.sympatico.ca/doc/robotone/for-sale.html

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? 2007?7?13???? UTC +8??3:39:41?Terry???

Sell: China Shenzhen ZHAOWEI Machinery & Electronics Co. Ltd engages in designing , manufacturing and marketing all kinds of electric motors. They are mainly suitable for the following applications: smart home application used in sm art kitchen and laundry, medical instrument for personal care, smart E-tran smission applied in automobile, industry automation applied in telecommunic ation and a great variety of plastic/metal planetary gearbox in different s izes. In order to develop the oversea market, we are current seeking new partne rs around the world to create a bright future together. ZhaoWei is a right choice and excellent partnership with sincere services.
Company: Shenzhen ZHAOWEI Machinery & Electronics Co., Ltd URL: http://www.zwgearbox.com/ Contact: Anny Liu Tel?+86-755-27322652 Fax?+86-755-27323949 E-mail: snipped-for-privacy@zwgearbox.com Add: Blk. 18, Longwangmiao Industry Park, Fuyong Tn., Bao?an Dist., Shenzhen 518103, Guangdong, China
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? 2007?7?13???? UTC +8??3:39:41?Terry???

Sell: China Shenzhen ZHAOWEI Machinery & Electronics Co. Ltd engages in designing , manufacturing and marketing all kinds of electric motors. They are mainly suitable for the following applications: smart home application used in sm art kitchen and laundry, medical instrument for personal care, smart E-tran smission applied in automobile, industry automation applied in telecommunic ation and a great variety of plastic/metal planetary gearbox in different s izes. In order to develop the oversea market, we are current seeking new partne rs around the world to create a bright future together. ZhaoWei is a right choice and excellent partnership with sincere services.
Company: Shenzhen ZHAOWEI Machinery & Electronics Co., Ltd URL: http://www.zwgearbox.com/ Contact: Anny Liu Tel?+86-755-27322652 Fax?+86-755-27323949 E-mail: snipped-for-privacy@zwgearbox.com Add: Blk. 18, Longwangmiao Industry Park, Fuyong Tn., Bao?an Dist., Shenzhen 518103, Guangdong, China
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