Bridgestone Corporation

Topcon Corporation

Sokkia Topcon Co., Ltd.

Yasutoshi Aoki

Yasutaka Enoki

Shigeo Makino

Takashi Kukimoto

Naoto Yamagishi

Shinji Usui

Kuninobu Kadota

Makoto Tsuruta

Akinobu Sugiura

Yuzo Kumagai

Yosuke Okudaira

Jun Abe

Yuichi Ohashi

Provided is a surveying instrument configured so that the optical axis of a guide light irradiation unit that irradiates guide light for guiding a survey operator and the optical axis of a lens barrel portion of a distance-measuring optical system become parallel to each other on a horizontal plane. The guide light irradiation unit is not disposed above the lens barrel portion that substantially matches a collimation direction is horizontally shifted with respect to the lens barrel portion. The horizontal shift distance D is configured so that a horizontal distance D between the optical axis of guide light and the optical axis of the lens barrel portion satisfies tan(&#x3b1;/2)&#xd7;Cmin&#x3e;D provided that &#x3b1; is an irradiation angle of the guide light in the horizontal direction, and Cmin is a shortest use distance of the surveying instrument.

Surveying instrument including guide light irradiation unit

The present invention provides a pneumatic radial tire for heavy load, having lug grooves in respective side regions of a tread surface, in which tire an amount of slip of the trailing edge of each of land portions defined by the lug grooves, with respect to a road surface, when the tire is rotated with load applied thereon is advantageously reduced without causing decrease in partial wear resistance of the land portions at a road contact surface thereof and generating cracks at the lug groove bottom. The pneumatic radial tire for heavy load, having a plurality of lug groovesprovided in respective side regions of a tread surfaceto extend in the tread width direction, open at respective side edges of the tread surface, and define land portionstherebetween, is characterized in that: in a cross section of each lug groovein the width direction thereof, only a groove wallon the step-in side of each land portionis bent at at least one bent point in the depth direction of the corresponding lug groovesuch that a portionof the groove wall, located on the inner side in the radial direction than the bent point f, is tilted in a direction that narrows a groove width.

Pneumatic radial tire for heavy load having lug grooves

[Problem] To provide an electro-optical distance meter in which the measurement time is reduced, and a temperature phase drift of electrical components is reduced. [Solution Means] An electro-optical distance meter includes a first light-emitting element () which emits light modulated with a plurality of main modulation frequencies (Fand F), a second light-emitting element () which emits light modulated with a plurality of adjacent modulation frequencies (F&#x2212;&#x394;fand F&#x2212;&#x394;f) close to the main modulation frequencies, respectively, first and second light receiving elements (and) which receive light emitted from both light-emitting elements, a first frequency converter group () connected to the first light receiving element, and a second frequency converter group () connected to the second light receiving element. The light emitted from the first light-emitting element is split into two parts, one of these is made incident onto the first light receiving element through a distance measuring optical path () for traveling to and from a target reflection object (), and the other is made incident onto the second light receiving element through a first reference optical path (), and the light emitted from the second light-emitting element is split into two parts, one of these is made incident onto the second light receiving element through a second reference optical path (), and the other is made incident onto the first light receiving element through a third reference optical path ().

Electro-optical distance meter

A tread of a heavy-duty pneumatic radial tire comprises a pair of upper and lower rubber layers having mutually different moduli of elasticity and a small-width groove formed in the upper rubber layer in such manner as to be substantially continuous in a circumferential direction of the tire. The dimension between a boundary surface bordering the two rubber layers and a bottom of the groove is set to be 1 mm or more. Accordingly, the arrangement prevents the occurrence of cracks due to a deforming stress acting in the groove bottom occurring when the tire rolls or rides on a curbstone.

Tread of heavy duty pneumatic radial tire

Automobile tire

A pneumatic radial tire comprises a pair of bead cores, at least one radial carcass ply comprised of a main body and a turnup portion, and a stiffener arranged between the main body and each turnup portion wound around each bead core, in which each stiffener is composed of first, second and third stiffener members, and a boundary surface X between the first and second stiffener members is inclined outward in the radial direction so as to approach to the main body and a boundary surface Y between the second and third stiffener members is inclined outward in the radial direction so as to separate away from the main body, and a ply end rubber member made from rubber having a hardness between the hardnesses of the first and third stiffener members is arranged on an outer end region of the turnup portion in the radial direction.

Pneumatic radial tires with stiffeners composed of three stiffener

An uneven wear-resisting heavy duty pneumatic tire comprises main grooves continuously extending in a tread of the tire along a circumference thereof, land portions separated by the main grooves, and stepped zones each provided in the land. Each stepped zone has a surface located radially inside of the tread by a step a viewed sectionally. Each of said stepped zones is separated from the adajcent land portions via a pair of circumferentially extending grooves or narrow cuts. An uneven wearing-sacrificing portion is formed by the surface of the stepped zone. The uneven wear-sacrificed portion slide-contacts with the tread within the tread ground-contacting area for supporting the load exerted upon the tire.

Heavy duty pneumatic tires preventing uneven wearing

An unvulcanized tread material for a pneumatic tire, including two layer members of a cap layer and a base layer and having a structure in which one or more portions of the base layer member project into the cap layer. The one or more portions of the base layer member project into the cap layer so as to respectively oppose one or more circumferential direction grooves to be formed in a manufactured tire. An interior of a mold is pressurized so that one or more convex portions, for forming a tire groove, of the mold and one or more projecting portions of the base layer member respectively contact. A manufactured tire in which the base layer member is exposed at bottoms of one or more grooves is formed.

Unvulcanized tread material for pneumatic tire, method of manufacturing

An uneven wear-resisting heavy duty pneumatic tire comprises main grooves continuously extending in a tread of the tire along a circumference thereof, land portions separated by the main grooves, and stepped zones each provided in the land. Each stepped zone has a surface located radially inside of the tread by a step a viewed sectionally. Each of said stepped zones is separated from the adjacent land portions via a pair of circumferentially extending grooves or narrow cuts. An uneven wearing-sacrificing portion is formed by the surface of the stepped zone. The unever wear-sacrificed portion slide-contacts with the tread within the tread ground-contacting area for supporting the load exerted upon the tire.

Heavy duty pneumatic tires including stepped tread zones for preventing

A heavy duty pneumatic radial tire includes a toroidal carcass consisting of plies having cords arranged in parallel with each other, and a plurality of belt layers interposed between the carcass and a tread of the tire. At least one of the plies has turn-up portions folded about a pair of bead cores from inside to outside of the tire. The tire comprises a crown protective layer arranged between the belt layers and the tread. The crown protective layer comprises wave-form cords or wave-form filaments. The tire further comprises a cushion rubber layer arranged radially inward of the protective layer and made of a rubber having a modulus less than 70 kg/cm.sup.2 under 100% elongated condition. A distance between cords of a radially outermost layer of the belt layers and the wave-form cords or the wave-form filaments of the radially innermost layer of the crown protective layer is more than 1.5 mm.

Heavy duty pneumatic radial tire

A method of producing tire belt comprises a first step of attaching a first belt ply to a forming drum having, at its axial ends, curved portions whose diameters reduce progressively toward axially outer ends of the curved portions. The first belt ply has a width wider than an axial length of the forming drum. The method further comprises a second step of expanding the forming drum so that diameters of the curved portions at axially outermost ends become a predetermined diameter smaller than a maximum diameter of the forming drum in the first step to deform a central portion of the first belt ply following to an outer contour of the forming drum, a third step of foldering ends of the first belt ply at axial outer ends of a second belt ply after attaching the second belt ply to a center portion of the first belt ply outwardly thereof, and a fourth step of attaching a third belt ply in plural layers onto the first and second belt plies outwardly thereof.

Growing community of inventors

Kodaira, Japan

Yasutoshi Aoki