Pennsylvania man crafts motorized pedal tractors
It's every toddler's fondest fantasy: A motorized pedal tractor. Bob Rentzel is the man who transforms those dreams into reality, but with a twist parents appreciate: A healthy dose of safety measures. "It's one thing to make a motorized pedal tractor," says Bob, who lives near York, Pa. "It's a whole different thing to make one that's safe enough to put a child on. I go the extra mile to make these safe."
Bob's fleet consists of four units powered by small gas engines: an Ertl International 56, an Ertl Case 1070, a Play-Trak (made by David Bradley for Sears), and an Ertl John Deere 20. Each tractor moves along at a sedate 2 mph, a perfect match for the average preschooler. "The kids just love them," he says. "Sometimes the parents have to pull the kids off the tractors. A lot want to get right back on."
The seed for Bob's fleet was planted when he saw a very young boy pilot a motorized Farmall pedal tractor in a Pennsylvania show's parade. In 1995, while recuperating from major surgery, Bob decided to tackle a similar project. A longtime collector of vintage tractors and equipment, he was amply familiar with the mechanics involved, and decades of experience working in power plant maintenance had trained him well in safety issues.
Bob's first project was the International 56. He began by cutting out the cast engine area of the body and fitting the tractor with an undermount frame. For power, Bob chose an old-style 1-1/4 hp Clinton because its internal oil pump ensures lubrication at most angles. Bob mounted the Clinton engine on the sub-frame, and he removed the engine's top-mounted gasoline tank, replacing it with two small tanks fitted under the hood, leaving the fuel supply high enough to use the engine's gravity-feed fuel system.
With the engine occupying the space where the steering shaft had been, a new steering system was in order. Bob made a short steering shaft for the steering wheel, passing through two bearings and with a T-shaped coupling just inside the body. A long steering bar extends vertically from the front axle through a bearing at the top of the casing. At the end of the bar is another T-shaped coupling just under the hood. Bob than ran cables from the rear coupling over a small pulley and to each side of the forward coupling. That system worked well, but cable failure was a problem until Bob replaced the cables with weed whip cord.
The clutch on the International is a simple belt tensioner, but since the power pulley is located on the engine's left side, Bob fabricated a crossover shaft for a gas pedal on the tractor's right side. That way, Bob notes, even very young children understand how to make the vehicle "go." Light pressure on the pedal moves the machine forward; release, and the pedal tractor stops. It took three gearing modifications, but Bob finally settled on a pair of jack shafts and sprocket stepdowns to keep the tractor to a speed safe for young operators. The rear wheel hubs are fitted with inner and outer ball bearings and grease zerks for lubrication.
By show season in 1996, the little red tractor was ready for use. If Bob had any doubts about the rig's appeal, they were laid to rest at the 1996 Red Power Roundup in Lebanon, Tenn. During that event, more than 300 children took turns at the wheel.
That success prompted Bob to build a second unit later that year. A collector of Case hydraulic drive garden tractors, he decided to use the same concept in a pedal tractor. From Joe O'Shea, Binghamton, N.Y., he acquired a Case 1070 tractor. Bob made slight modifications: He mounted a small hydraulic motor on the tractor's left side where the pedal shaft came through. On the right side, he installed a rotary valve with a spring return and fitted with a foot pedal. As with the International, Bob modified the rear axle hubs. But this time, he made a locking rear end so both drive wheels would pull at all times. Next, he hooked a trailer carrying a 2-1/4 hp Clinton engine to the tractor, with a Cub Cadet hydraulic pump coupled to the engine. The hydraulic pump feeds oil at 400-500 psi to a control valve on the tractor. The control valve sends oil to the hydraulic motor that drives the tractor, then back to an oil cooler and an expansion tank on the trailer.
In 1997, Bob swapped a small motorcycle for a motorized pedal tractor, a Play-Trak made by David Bradley for Sears in the early 1960s. Powered by a 2-1/2 hp Tecumseh engine, the unit is clutched by a belt tensioner housed in an enclosed guard on the left side, and a foot pedal on the right side. The rear axle is extended to allow for an external ratchet on the inside of the rear wheels that lets both wheels drive and slip as needed on turns.
The next tractor would prove to be Bob's most challenging: a hydraulic track-type motorized pedal tractor. This time he turned to an Ertl-made John Deere Model 20 pedal tractor in his collection. With a John Deere crawler in mind, Bob disassembled the John Deere 20 and welded 5-1/2 inches of 1/8-inch aluminum stock between the two cast body sides, making the unit wide enough to hold a 2 hp Briggs & Stratton engine. Then it was back to Binghamton, N.Y., to meet with O'Shea to discuss the tracks and drives on the crawlers Joe had made. They settled on no. 40 agricultural chain, and Joe had 6-inch sprockets cast, using a corn planter sprocket for a pattern.
Next, Bob built a frame to carry the engine, hydraulic pump, two hydraulic motors, track adjustors, front sprockets and track roller units. On the body of this machine, the final drive sprockets and shafts all run on ball bearings. The expansion tank for the oil is patterned after one on a John Deere 350 dozer tank. The control valves and levers, seat and arm boxes are all part of the upper body. "This unique design presented many challenges," Bob says, "but by using hoses we were able to have a pivot point in-line with the final drives and I am able to unlatch the unit at the front and tilt up the body for maintenance." The two hydraulic motors used to drive the tracks are controlled separately by two Parker-Hannifin open-center valves mounted under the floor plate with short control levers up through the floor.
PVC pipe is used for the two control levers, which provide even the youngest operators plenty of leverage. This is also a safety measure for the control valves: If a bigger child should push the levers to the side, they will break off, protecting the valves.
Open-center valves allow this small engine to idle. The two valves send pressure to each hydraulic motor. Steering is quick, responsive and easy. "We have had 18-month-old kids with pacifiers in their mouths coordinate and move this machine," Bob says.
Safety is the key to Bob's creations, and it's a motivation he takes very seriously. "I put a lot of thought into safety," he says. Indeed, he's considered every element of each pedal tractor. He's put wheel weights on one to make it more stable. He's covered chains, sprockets and exhaust pipes to protect children's hands and feet from injury. He's altered gearing to prevent any possibility of a tractor or trailer from rolling on its own. He's put a protective guard around an exposed engine, installed valves to keep pressure low, built shields to block access to tracks and added control valves to ensure the tractor stops when pressure on the foot pedal is released.
Bob's concern for safety doesn't end with the mechanicals. He rarely runs more than one unit at a time. "We watch them real close," he says, "because you never know what a kid's going to do." Every rider is carefully instructed to keep both feet on the tractor at all times. Pedal tractors not in use are kept on trailers out of reach of children who would clamber over them. "Very few kids that age could start an engine anyway," Bob says. "But we still keep them off of the tractors when they're not on a ride."
Some suggest that children should not be allowed to play with such mechanical marvels. Bob wouldn't have it any other way. "It's no good to me if I can't see kids having a good time," he says. "I just love seeing the kids have fun on them. I get a lot of enjoyment out of that."
- For more information: Bob Rentzel, 5380 Board Road, Mount Wolf, PA 17347; (717) 266-4490.