In 2008, construction of an auxiliary spillway began at the Folsom Dam near
Sacramento, CA. This Joint Federal Project (JFP) is managed by the U.S. Army Corps
of Engineers, together with other Federal and state agencies. The new spillway will
allow water to be released earlier and more safely from Folsom Lake during a high
Granite Construction is the general contractor for the overall project which includes a
control structure containing six submerged tainter gates and six bulkhead gates. The
massive 45 ft. tall, 30 ft. wide curved tainter gates rotate in an arc and are hydraulically-
operated to allow for precise water flow control. The new control structure’s tainter gates
will work in conjunction with the dam’s main gates to release water from the lake and
funnel it through 3,000 ft. long spillway into the American River below.
Positioned upstream from the tainter gates, the six 39 ft. long, 23 ft. wide and 3-1/2 ft.
thick flat steel bulkhead gates are raised and lowered vertically to completely stop water
flow in order to allow maintenance work on the tainter gates.
Engineering teams at Nuttall Gear and Delroyd Worm Gear worked closely with Linita
Design and Manufacturing, the firm responsible for the design and assembly of the
spillway’s gate systems. Nuttall and Delroyd developed and manufactured heavy-duty,
custom-designed primary and secondary reducers to meet the specific application
requirements of the bulkhead gate drivetrains.
Ameridrives Couplings, also part of Altra Industrial Motion, was chosen to provide all the
required gear couplings for all the bulkhead gate drivetrains based on their reputation for
quality and reliability in tough industrial applications.
Delroyd Worm Gear: Custom Drives
Primary Drive Worm Gear Reducers: Input rating: 15 HP @ 1160 RPM,
Reduction ratio: 11.4:1, Output torque rating: 18,750 lb.in.
Delroyd helical worm gear drives feature a hardened, ground and polished alloy steel
worm that develops a smooth, work-hardened surface on the bronze gear providing
high efficiency and long service life.
Nuttall Gear: Custom Drives
Secondary Reducers (with double extended shafts): Input rating: 15 HP @ 102 RPM,
Reduction ratio: 238:1, Output torque rating: 4,412,000 lb.in.
All Nuttall drives are made in the USA and feature carburized and ground gearing with
CWI weld inspected, fabricated steel housings.
Ameridrives: Amerigear Couplings
9.44" dia. gear couplings connect the primary gearbox with the secondary gearbox.
30.5" dia. gear couplings connect the primary gearbox with the open pinnion.
Amerigear flexible couplings feature fully-crowned teeth for higher torque, higher speed and higher
misalignment capacity (1.5 angular misalignment per gear mesh). Units also feature accurately
machined, medium carbon steel hubs and sleeves. Positive-type O-ring seals keep lubricant in
and contaminants out. Seals are enshrouded to prevent damage.