Title: Safety-guard for a crane

Abstract: A safety-guard for a crane having a boom, comprising stress-detecting means which is provided to lifting hydraulic cylinder unit for the boom so as to detect a stress applied to the cylinder unit in the direction along the axis of said unit and to give out a signal, one or more functional potentiometers which correspond to respective spans of the boom and give out safety-limit stress-reduced signals at the concerned span of the boom respectively with the movement of movable contacts that are moved in response to the vertical revolution of the boom, and a safety device which receives said signals coming from the stress-detecting means and one of the functional potentiometers corresponding to the concerned span of the boom and indicates the concerned ratio of operation of the crane or gives a warning on falling-down and/or breaking-down of the crane. Thus, operator can catch operation state of the crane with ease for a safe operation of the crane.

Do you think this is a good invention? Vote now:

Votes so far: For:(0) Against:(0)
Other info:

Inventors: Shinohara, Shinitsu (Takamatsu, JA)
Uchino, Hisanori (Tokyo, JA)
Yamaji, Hiroyuki (Kagawa, JA)

Application Number: 266355
Filing Date: 1972-06-26
Publication_date: 1977-08-02
Assignee: Tadano Ironworks Co., Ltd. (Takamatsu, JA)
Primary Class(es): 212/278 73/862.56, 177/146, 177/211
Other Classes:
US Patent Ref:

2477854	Aug, 1949	Baker	73/141.
2616683	Nov, 1952	Le Fevre	177/211.
2761670	Sep, 1956	Fouretier	177/211.
2765654	Oct, 1956	Greer et al.	177/147.
3339652	Sep, 1967	Price	177/147.
3489294	Jan, 1970	Greb et al.	212/39.
3618064	Nov, 1971	Hamilton	340/267.
3641551	Feb, 1972	Sterner et al.	212/39.
3724679	Apr, 1973	Brownell et al.	212/39.
3740534	Jun, 1973	Kezer et al.	212/39.
3909817	Sep, 1975	Pietsch et al.	340/267.

Other Refs: 1,268,340

May, 1968	DT

Primary Examiner: Blunk, Evon C.
Assistant Examiner: Rowland, James L.
Attorney: