Finishing touches

Concrete Construction, Oct, 2004 by Tom Klemens

Concrete finishing is an art that requires strength, skill, and good judgment--the finisher's tools make it possible to execute that artistry. Stone Construction Equipment, Honeoye, N.Y., recently received a patent for an enhancement to its walk-behind power trowel line that makes this powerful tool a nearly seamless extension of the person finishing the concrete.

Introduced as a patent-pending option a couple of years ago, Stone's ProPitch power trowel blade adjustment mechanism was a natural outgrowth of its variable fine-tuning blade adjustment. While its original adjustment system allowed power trowel operators to adjust the pitch of the blades to precisely the desired angle, the adjustment speed was limited by how quickly the operator could rotate the control knob.

The ProPitch system uses a lever on the handle with a system of pivots and linkages that creates a 7-to-1 mechanical advantage. That combination allows operators to adjust blade pitch quickly, on the fly, with very little effort. Also the single-handed adjustment can be made without relinquishing control of the machine.

The control lever follows a guide arc at the upper end of the handle. As the operator pulls the lever to raise the blades, a cam lock system inside the lever mechanism automatically grips the guide are, maintaining the desired blade pitch. Unlike using a ratchet, which allows for only a series of preset pitches, to hold the blades in position, the cam can grip anywhere along the guide are, allowing for very fine adjustments.

When the time comes to reduce blade pitch, whether it's a slight adjustment or returning to a zero pitch, the operator simply depresses the push-button thumb trigger, which releases the cam and moves the lever toward the trowel. The adjustment is smooth and quick, and takes very little effort.

Stone offers the ProPitch blade adjustment option on its 36-, 46- and 48-inch power trowels. For more information on this product, visit www.stone-equip.com or Circle 11.

--Tom Klemens