Abstract: In a scanning spectrophotometer, in which a narrow wavelength band of radiation can be selected from a range of wavelengths for transmission alternately through a sample cell and a reference cell, continuous automatic baseline correction is provided. A pulse train signal is generated, wherein the number of pulses represents the ratio of a parameter (e.g., intensity) of the radiation transmitted, respectively, through the sample and reference cells. A ratio of unity represents the baseline, and deviations from the baseline are indicated by changes in the number of pulses in the pulse train. Digital information indicative of baseline deviations is stored in a memory device when the spectrophotometer is being calibrated, and is retrieved from the memory device during operation of the instrument for sample analysis. The retrieved information generates a correction signal, which provides a continuous baseline correction.

Abstract: A belt-driven transmission designed particularly for self-propelled, walking lawn mowers is provided. The transmission is mounted on a deck of a mower between a front pair or a rear pair of wheels and is driven through a pulley on the engine drive shaft and a pulley on the transmission connected by a belt. With this arrangement, the engine requires no special power take-off shaft to drive the mower. Consequently, the transmission can be universally applied to many different self-propelled lawn mowers. The new transmission can also be equipped with a deadman's clutch. Further, it can be provided with a manually-adjustable pulley of variable diameter to provide different speeds and torque for the drive shaft of the driven wheels. Also, in accordance with the invention, the drive shaft has a ratchet coupling device near each driven wheel to provide a differential effect for the wheels when the mower is being turned.

Abstract: A compact transmission designed particularly for a self-propelled, walking lawn mower is provided. The transmission is mounted on the deck of the mower behind the engine and is connected to a power take-off shaft of it. The transmission has two forward speeds and is shifted by a short finger-operated shift lever extending rearwardly. The transmission is compact, light in weight, and low in cost. These are achieved, in part, by the gears being arranged to occupy a minimum space and a one-piece shifter fork and guide plate being made of plastic material and assembled through an opening in the top of the transmission housing. The transmission housing also can use either a horizontal or a vertical input shaft with minimum change in design.

Abstract: A transmission with multiple forward speeds and an improved shifting arrangement is provided. The transmission is particularly adapted for use on riding lawn mowers, garden tractors, and the like. The shift mechanism includes a pivotable shift lever which requires the operator to interrupt the motion of the lever when shifting from neutral to reverse and from neutral to successive forward speeds. This enables the operator to know by feel what gear the transmission is in. The transmission can also be quickly shifted from reverse to neutral or from any forward speed down to or toward neutral without interruption. The pivotable shift lever is located outside a cover of the transmission and is mechanically connected through the cover with an internal shift lever or arm which engages a pawl pivotally mounted on a carrier, with a stop member being engageable by the pawl to control the movement of the carrier, the pawl, and the levers.