A CONVERTIBLE BRAKE, RUDDER PEDAL By Richard J. Halstead (EAA 67, 160) Chapter 339 2321 Drum Creek Road Chesapeake, Virginia 23321 (804) 483-5651 Business - (804) 488-5029 Home

w,

H EN I STARTED building a Taylor Monoplane over three years ago, I started shopping for an appropriate set of wheels for the ultra light. Since the plans called for a set of wheels without brakes, I happily settled on a set of Azusa 5 inch wheels. As the project progressed, I decided to build up rudder pedals with built-in toe brakes for a hydraulic brake system. Having access to a metal brake, I designed aluminum pedals to accommodate hydraulic cylinders with a standard 8 inch center to center mounting distance as seen in Fig. 1. My problems began to develop when I tried to find hydraulic calipers that would fit the aforementioned wheels. I finally gave up the hope of hydraulics and bought Azusa's matching 4'/2 inch mechanical drum brakes. Now I had a system with a missing link. How was I going to connect mechanical drum brakes to rudder pedals with provision for toe brakes? I poured through every piece of reference literature I had, including many back issues of SPORT AVIATION. The only article I could find was one by Tony Bingelis on brake installations. Being a first time builder, I have infinite respect for Tony's knowledge and ability. But I wasn't completely satisfied with Tony's suggestion of running the mechanical cables over pulleys at the base of the rudder pedals and up to the toe pedals. Several ideas went down the drain until I finally settled on the arrangement shown in Fig. 2. This system was based on

FIGURE 1

FIGURE 2

using a conversion of the existing pedals. By using a

tie rod from the toe pedal down to a bell crank located at the rudder pedal base, I found the cable pull point remained stationary at the same time the toe pedal remained in a very close plane with the rudder pedal throughout its full travel. About the time I finally came up with this idea, I discovered that John Monnett was selling a cable set made for the exact brakes I had purchased. So the pieces were beginning to fall together. Things looked so good at this stage, I figured all I needed now was a very simple and light parking brake arrangement. Several sketches went into the basket and the last one looked like the answer. In essence, it's a spring loaded detent plate that normally rides along with the bellcrank when the toe pedal is actuated. To apply the parking brake, the detent plate is pulled rearward at the same time the pedal is depressed. This unlocks the detent plate which when now released to its spring loaded forward position will engage the uplifted bell crank tie rod and prevent it from dropping back to its normal resting position. The detent plate has

ADAPTER ARM

FIGURE 3

three locking positions to compensate for cable stretch and/or brake lining wear. Figure 2 shows a short connecting link needed between the bell crank and the

rassment. The pads were pop-riveted to the pedals and can easily be replaced. All fiat metal parts except the

cable end. This was required because the fixed cable length didn't quite reach the bell crank and a cable

pedals and stainless hinges are made from .090 thick 4130 steel. The cable link is made of .062 thick 4130. The tie rod is .187 DIA drill rod threaded #10-32. The basic idea can obviously be adapted to other types of pedals, both wood and metal. The author has submitted this article in the hopes of helping other suffering first time builders and will supply full size prints of the system to anyone sending a large, stamped, selfaddressed envelope.

end adaptor was needed any way. The system components are shown in Figure 3. The ribbed rubber pads shown were part of a bicycle pedal adapter block kit put out to compensate for kiddies with short legs. This seemed like a good safety feature after reading of wet shoes slipping off rudder pedals

and causing a considerable hazard as well as embar18 JANUARY 1977