A Double Mutterer is an important adjunct to the belt driven power trains of machinery engineered during the late 19th century for the printing of newspapers. It is a sub-assembly of a cable driven system of Newtonian governors which presumably acts as a regulating servomechanism. The Double Mutterer's function is to moderate slack and thereby reduce horsepower drain and achieve fuel efficiency. When not properly functioning, an unacceptable level of component breakdown and unplanned production downtime is known to be routine.
An incomplete description of the component operation of a Double Mutterer involves the distortion of an impact load applied to a helical gear from an oscillating slotted bar which disengages an antiparallel linkage of a friction drive and puts a wormwheeled pantograph into play. [ 1 ]
When operating correctly, a power train properly regulated by the Double Mutterer should run as, "smoothly and quietly as an owl's swoop." Without the Double Mutterer, the belts of the drive train can be observed to flap about the flywheels, "like the flesh of a sprinting fat man."
Most of this vintage of machinery in which a Double Mutterer is a component has long since been retired. A single known exception is known to still be in production at the turn of the millennium at The Sun, published twice daily in New York City. Only a single master mechanic is known to have an expert understanding of this equipment at the turn of the millennium. Before this individual's relatively recent employment at The Sun, a functional understanding of this vintage of machinery has been lost even to mechanics who have spent their entire careers working on those machines and had been trained on them by their own fathers.
In addition to the severely limited expertise needed to maintain equipment such as this, it is likely that there may be an unavailability of consumables required to maintain them. For example, the Double Mutterer employs a friction brake which must be regularly lubricated with the finest spermaceti for ideal operation. The International Whaling Commission banned whaling in 1986, so it is most likely that spermaceti is now unavailable and inferior substitutes must be employed.
When properly maintained, a functioning Double Mutterer should achieve power-train belt life of six months to a year. When not functioning, powertrain breakdowns can be expected as often as once a week and include premature belt wear, shaft wear and breakage.
[ 1 ] Helprin, Mark. Winter's Tale. Houghton Mifflin Harcourt Publishing Co. p.462-464