Abstract: A cryopump includes a cryopanel, a main body, and a baffle plate. The cryopanel is connected to a refrigerator. The main body accommodates the cryopanel. The baffle plate is located in a gas inlet of the main body. The baffle plate includes a first portion and a second portion. The first portion includes a center of the baffle plate and a first hole extending through the baffle plate. The second portion includes an edge of the baffle plate and a second hole extending through the baffle plate. The second portion has a greater conductance than the first portion.

Abstract: A cryopump includes a cryopanel, a main body, and a baffle plate. The cryopanel is connected to a refrigerator. The main body accommodates the cryopanel. The baffle plate is located in a gas inlet of the main body. The baffle plate includes a first portion and a second portion. The first portion includes a center of the baffle plate and a first hole extending through the baffle plate. The second portion includes an edge of the baffle plate and a second hole extending through the baffle plate. The second portion has a greater conductance than the first portion.

Abstract: A material hardness distribution display system (10) includes a probe unit (20) in which a plurality of probe elements (22) are two-dimensionally arranged. Each of the probe elements (22) has an oscillator (26) for introducing oscillation into a biological tissue and an oscillation detection sensor (28) which detects a reflected wave. The probe elements (22) are successively selected by a switch circuit (50) and connected to a hardness calculation unit (70) and a measurement depth calculation unit (82). The hardness calculation unit (70) executes a frequency component analysis for an incident wave signal to the oscillator (26) and a reflected wave signal from the oscillation detection sensor (28) to calculate the hardness of the biological tissue on the basis of the analysis results.

Abstract: A material hardness distribution display system (10) includes a probe unit (20) in which a plurality of probe elements (22) are two-dimensionally arranged. Each of the probe elements (22) has an oscillator (26) for introducing oscillation into a biological tissue and an oscillation detection sensor (28) which detects a reflected wave. The probe elements (22) are successively selected by a switch circuit (50) and connected to a hardness calculation unit (70) and a measurement depth calculation unit (82). The hardness calculation unit (70) executes a frequency component analysis for an incident wave signal to the oscillator (26) and a reflected wave signal from the oscillation detection sensor (28) to calculate the hardness of the biological tissue on the basis of the analysis results.

Abstract: The invention has an object to provide a regenerator and cryogenics pump using a regenerator material which fulfills such requirements as specific heat, thermal conductivity, manufacturing easiness, strength, hardness, chemical stabilization and low cost instead of Pb which is environmentally harmful. In a regenerator 14 which contains regenerator material 16 in an internal path for refrigerant, and in which heat is exchanged between the helium gas as refrigerant, and regenerator material, regenerator material 16 is any one of Sn, Bi—Sn alloy and Ag—Sn alloy. The regenerator material 16 is spherical. Plural spheres are packed in the internal path of the regenerator 14.

Abstract: In a hardness measurement system, selecting an operating frequency is facilitated by using a phase shift circuit. A hardness sensor is connected to an operating frequency selection apparatus and in a free end state the amplitude versus frequency characteristic is acquired, and the frequency and the phase of the peaks are measured and acquired as the free end characteristic. Next, the hardness sensor is placed into contact with a first test piece, and the frequency and the phase that change for the peaks are measured and acquired as the first characteristic. The same procedure is performed for a second test piece that is harder than the first test piece to yield the second characteristic. Based on these characteristics and a predetermined selection criterion a peak suitable for hardness measurement is selected and the operating frequency is set from the frequency of the peak.

Abstract: The selection of an operating frequency is further facilitated in a hardness measurement system for measuring the hardness of an object using a phase shift circuit. A hardness sensor is connected to an operating frequency selection apparatus and in a free end state the amplitude versus frequency characteristic is acquired, and the frequency and the phase of the peaks are measured and acquired as the free end characteristic (S10-S20). Next, the hardness sensor is placed into contact with a first test piece, and the frequency and the phase that change for the peaks are measured and acquired as the first characteristic (S22-S28). The same procedure is performed for a second test piece that is harder than the first test piece to yield the second characteristic (S30-S36). On the basis of these characteristics, the selection of a peak suitable for hardness measurement is performed on the basis of a predetermined selection criterion and the operating frequency is set from the frequency of the peak.

Abstract: The invention has an object to provide a regenerator and cryogenics pump using a regenerator material which fulfils such requirements as specific heat, thermal conductivity, manufacturing easiness, strength, hardness, chemical stabilization and low cost instead of Pb which is environmentally harmful. In a regenerator 14 which contains regenerator material 16 in an internal path for refrigerant, and in which heat is exchanged between the helium gas as refrigerant, and regenerator material, the regenerator material 16 is any one of Sn, Bi—Sn alloy and Ag—Sn alloy. The regenerator material 16 is spherical. Plural spheres are packed in the internal path of the regenerator 14.

Abstract: An optically active tetrahydropyran derivative represented by one of the following general formulae, a liquid crystal composition containing the derivative, and a liquid crystal device containing the composition are disclosed. The optically active tetrahydropyran derivative is a novel compound which is chemically stable, causes no coloring, has excellent optical stability, and shows a large spontaneous polarization and a quick response. The optically active tetrahydropyran derivative can show a more excellent quick response when it is used in a composition, and is useful as a component in a ferroelectric liquid crystal which induces a large spontaneous polarization.

Abstract: There are disclosed a novel optically active tetrahydropyrane derivatives (for example, (2R,5R,6R)-tetrahydro-6-trifluoromethyl-2-hexyloxy-5-(4"-hexyloxybiphenyl) -4'-carbonyloxy)pyrane; (2S,5R,6R)-tetrahydro-6-trifluoromethyl-2-hexyloxy-5-(4"-hexyloxybiphenyl) -4'-carbonyloxy)pyrane, etc. may be mentioned.) represented by the formula (I): ##STR1## or (I'): ##STR2## wherein symbols in the formula are as described in the specification, which is available as a liquid crystal material used for a display device or an electro-optic device, a liquid crystal composition and a liquid crystal device containing the same.The optically active tetrahydropyrane derivative of the present invention can improve high speed response particularly when it is made a composition, and is available as a compositional component for a ferroelectric liquid crystal which induces a large spontaneous polarization.

Abstract: There are disclosed a novel optically active tetrahydropyrane derivatives (for example, (2R,5R,6R)-tetrahydro-6-trifluoromethyl-2-hexyloxy-5-(4"-hexyloxybiphenyl) -4'-carbonyloxy)pyrane; (2S,5R,6R)-tetrahydro-6-trifluoromethyl-2-hexyloxy-5-(4"-hexyloxybiphenyl) -4'-carbonyloxy)pyrane, etc. may be mentioned.) represented by the formula (I): ##STR1## or (I'): ##STR2## wherein symbols in the formula are as described in the specification, which is available as a liquid crystal material used for a display device or an electro-optic device, a liquid crystal composition and a liquid crystal device containing the same.The optically active tetrahydropyrane derivative of the present invention can improve high speed response particularly when it is made a composition, and is available as a compositional component for a ferroelectric liquid crystal which induces a large spontaneous polarization.

Abstract: There is disclosed an optically active fluorine-containing compound represented by the general formula (I) ##STR1## wherein Rf is a fluoroalkyl group having 1 or 2 carbon atoms; R.sup.1, R.sup.2 and R.sup.3, independently of one another, are each a hydrogen atom, a straight or branched chain alkyl group having 1 to 15 carbon atoms, an alkenyl group having 2 to 15 carbon atoms or an aralkyl group having 7 to 10 carbon atoms; and * is an asymmetric carbon atom. The above compound has a fluoroalkyl group with a remarkable electron-attracting property at the asymmetric carbon atom in the tetrahydropyran ring. It is exemplified by tetrahydro-6-trifluoromethyl-2-hexyloxy-4-methyl-5-hydroxypyran and expected to find a wide variety of useful applications as raw materials for an enzyme inhibitor, a bioactive substance, a carcinostatic, a ferroelectric liquid crystal, etc.

Abstract: A planetary gear type forward and backward drive switching apparatus, comprising a sun gear mounted on an input transmission shaft, a carrier mounting planetary gears meshing the sun gear and rotatable about the transmission shaft, a ring gear meshing the planetary gears and rotatable about the transmission shaft, and a friction brake mechanism for selectively braking rotations of the carrier and the ring gear, including a ring-formed main brake body having braking faces for acting on side faces of the carrier and the ring gear, the main brake body being shiftable axially of the transmission shafts for selectively braking the carrier and the ring gear, a clutch mechanism for selectively transmitting rotational outputs of the carrier and the ring gear to an output transmission shaft, and a control lever for controlling the forward and backward drive switching apparatus.

Abstract: A change speed apparatus for a tractor comprising a combination of frictional stepless change speed means and planetary reduction means. A large diameter gear is used to drive the frictional stepless change speed means by means of engine output, and the frictional stepless change speed means includes a large diameter driven disc which engages an outer periphery of an internal gear of the planetary reduction means to be axially movable but not rotatable relative to the internal gear. The planetary reduction means is located in a space defined by the large diameter gear and the frictional stepless change speed means.

Abstract: An agricultural tractor comprising differential case, a transmission case, a speed change case interposed between the two cases and directly coupled thereto, and a speed change mechanism contained in the speed change case and adapted to provide a great reduction ratio. The speed change case is not integral with the two other cases.

Abstract: A tractor travelling system transmission mechanism for providing tractor travelling system stepless speed change including the stop status of a tractor, and tractor forward/backward changeover, by using a friction type stepless transmission means, a planet reduction gearing and a forward/reverse changeover gearing, which is independently disposed without commonly utilizing the friction type stepless transmission means or the planet reduction gearing as a forward/reverse changeover means.

Abstract: In a farm tractor of four wheel drive type, a speed change device for a power takeoff shaft projecting from a rear portion of a transmission case for driving a work implement attached to the rear end of the tractor is mounted in the rear portion of the transmission case, and a main shaft to receive output of the engine, a pinion shaft for driving the rear wheels and a transmission shaft for driving the front wheels are mounted in the front half of the transmission case with minimum spacing between the three shafts. This arrangement permits the transmission case to be compact in the vertical as well as transverse directions and provides a large space in the tractor underbelly for attaching a work implement.

Abstract: A tractor transmission mechanism in which power ON/OFF operations of the travelling system and the PTO system may be carried out in succession by double action clutch means by utilizing a tractor transmission case of the type in which power ON/OFF operations of the travelling system and the PTO system are carried out at the same time by a main clutch.

Abstract: A speed change mechanism for a transmission comprises a main shaft provided with a plurality of power transmitting gears, and a propelling speed change gear system and a power takeoff speed change gear system supported on the opposite sides of the main shaft in parallel thereto. Each of the propelling and power takeoff speed change systems includes a speed change shaft freely rotatably carrying a suitable number of speed change gears meshing with the power transmitting gears on the main shaft at all times. The speed change shaft accommodates an axially slidable speed change rod which, when moved, forces pins outward or inward radially of the shaft to couple the speed change shaft to the corresponding speed change gear or disconnect the shaft from the gear. The freely rotatable speed change gears are held against axial movement, while axially slidable engaging members which are otherwise provided between the adjacent speed change gears are eliminated.

Abstract: In a power transmission system in which the torque delivered to an input shaft is transmitted to an output shaft via a planetary gear speed reduction mechanism, a stepless speed change system comprising a stepless speed change mechanism including a disk operatively connected to a gear mounted on the input shaft, a roller in contact with the disk and shiftable diametrically of the disk in a direction intersecting the axis of rotation of the disk, and a handle lever for shifting the roller, the roller being rotatable by the disk in a positive or reverse direction or stoppable when positioned at the center of rotation of the disk; and a worm and a worm wheel for transmitting the positive or reverse rotation of the roller to an internal gear of the planetary gear mechanism. When the output shaft is subjected to a load, part of the resulting counteracting torque is fed to the input shaft through the stepless speed change mechanism.