That's not correct! It's the gear ratio! Not friction that makes the
worm gear winch self braking! I can raise my LM470 tower to vertical
with one hand using my Dayton worm gear winch. With the double step
down spur gear winch I could barely raise it with two hands. It was
work for a guy considerably larger than I. Yes the recirculating ball
step down has very little friction, but find one that's affordable to
hams, that doesn't require modification to make it useful. Electric
cars do use dynamic breaking (I have one), but they still require
mechanical brakes. Dynamic breaking only slows the car. The worm gear
drive is still the most viable option.
A good worm gear winch has more friction than a spur gear winch, but
turns "MUCH EASIER" than a spur gear winch for the same load. I have
a good Dayton worm gear drive winch. Use a good grease meant for high
contact pressure such as BR2 grease. (
http://www.dowcorning.com/applications/search/products/details.aspx?prod=01512854&type=PROD
) and well worth the price. You don't need a lot.
Hand Winch,Worm Gear,No Brake,3000 lb.
<https://e.grainger.com/pub/cc?_ri_=X0Gzc2X%3DWQpglLjHJlYQGmzbAg90zcGBzbzbYzeHp3wIUAzdNmgRO6y3LWVXtpKX%3DSSDUU&_ei_=Ent1lRLEeJUBGfe13xjMWihlbL5B_TL70smvptjF2afSqEKQ3FpP2cXN-5_GE_Y9TGX5YmZr7yLJT2xhS2S_h_zr_eAF7MFWB3bKFetdkqSjaWruhQBQ10ehAQW5xTapnc8x7GZsejZbppQrKXLxNOniuw45H_qK_RFoB55Xew3bcoLdhHLqY0Cq_CSAaHUeUUfIOHkRdJIKmnAq1DSomXUg9W0cfU-2ltkrZwj_4giFv1XJB3fsGdYInn28Dz90PesiExTi0bMStsk_T3cqGs0gF_G1UQ6DldrFyj7ALg.>
Item No: 12U381
<https://e.grainger.com/pub/cc?_ri_=X0Gzc2X%3DWQpglLjHJlYQGmzbAg90zcGBzbzbYzeHp3wIUAzdNmgRO6y3LWVXtpKX%3DSSDUW&_ei_=Ent1lRLEeJUBGfe13xjMWihlbL5B_TL70smvptjF2afSqEKQ3FpP2cXN-5_GE_Y9TGX5YmZr7yLJT2xhS2S_h_zr_eAF7MFWB3bKFetdkqSjaWruhQBQ10ehAQW5xTapnc8x7GZsejZbppQrKXLxNOniuw45H_qK_RFoB55Xew3bcoLdhHLqY0Cq_CSAaHUeUUfIOHkRdJIKmnAq1DSomXUg9W0cfU-2ltkrZwj_4giFv1XJB3fsGdYInn28Dz90PesiExTi0bMStsk_T3cqGs0gF_G1UQ6DldrFyj7ALg.>
It makes lifting a given load much easier, but compared to spur gear
winches it's not cheap @ $249 Vs $50 or $60 for the spur gear drive
winch at the local Ace hardware store.
Just try running a good worm gear winch with (with grease applied) no
load to see how much friction it has.
Note: Worm gear drive rotators are popular for swinging large arrays
with small motors and do not require brakes, but they are pricey
compared to the ham series rotators by Hy-Gain.
Also, the spur gear driven winch can be dangerous. I lost a lot of hide
off the back of my hand to the handle on one. If your hand slips off the
handle, just step back and let it go.
73
Roger (K8RI)*
*
On 6/29/2015 1:25 PM, Richard (Rick) Karlquist wrote:
On 6/29/2015 8:53 AM, Patrick Greenlee wrote:
There is more than one type of winch brake. Worm drives above a certain
reduction ratio won't "motor" or allow the load to turn the winch. There
are no brake parts as such but you get full control and if you turn lose
of the handle the load will not be able to turn the winch. No brake
parts = no brake parts to wear or overheat in use.
There is no free lunch with worm drives. The worm drive IS a brake
that is "ON" ALL the time, whether going up or down or standing still.
As such, it causes at least a 2X increase in effort going up. Going
down, the same friction applies so that you have to apply significant
effort even with help from gravity. All this extra effort due to
friction HEATS up the worm gear. If you replaced the worm drive with
a recirculating ball bearing drive as used in vehicle steering, it
would get rid of the friction and also get rid of the self braking.
When you lower a tower, the gravitation energy has to go someplace,
meaning it gets converted to heat.
What is really needed is a braking system like they use for electric
cars where the energy is fed back into the battery. Probably not
cost effective vs $150 winches.
Rick N6RK
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73
Roger (K8RI)
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