Hitachi Construction Machinery Co., Ltd.

Kazuhisa Ishida

Masami Ochiai

Tsutomu Udagawa

Teruo Igarashi

Toshimi Sakai

Kouji Funato

Akira Nakayama

Shinobu Higashi

A winch over-winding prevention apparatus includes: a winch drum that is driven for up/down hoist in response to a command issued through an operating lever; a stop switch that is activated when a suspended object raised or lowered as a hoisting cable wound around the winch drum is further taken up or fed out is hoisted up to a predetermined stop position; and a stop device that stops drive of the winch drum when the stop switch is activated, and further includes: a speed detection device that detects a hoist speed of the suspended object; a speed reduction device that reduces a drive speed of the winch drum once the suspended object reaches a predetermined speed reduction start position; and a speed reduction control device that calculates a deceleration rate of the winch drum in correspondence to the hoist speed of the suspended object detected by the speed detection device and controls drive of the speed reduction device in response to a speed reduction command corresponding to the deceleration rate.

Overwinding prevention device for winch

A swivel control apparatus according to the present invention , includes: a hydraulic pump; a hydraulic motor for swiveling which is driven by hydraulic oil emitted from the hydraulic pump; a control valve which controls a flow of hydraulic oil which is supplied from the hydraulic pump to the hydraulic motor for swiveling, and at a neutral position of the control valve cuts off from one another a pair of ports which communicate to input and output ports of the hydraulic motor; a valve device which communicates and cuts off from one another a pair of conduits which are respectively connected to the input and output ports of the hydraulic motor for swiveling; a pressure detection device which detects respective pressures in the two conduits and outputs pressure signals; a rotational speed detection device which detects a physical quantity based upon a rotational speed of the hydraulic motor for swiveling and outputs a rotational speed signal; a mode selection device which selects a neutral brake mode and a neutral free mode; and a control device which controls driving of the valve device so as to cut off the two conduits from one another when the neutral brake mode is selected, and so as to communicate the two conduits based upon the pressure signals and the rotational speed signal when the neutral free mode is selected.

Swivel control apparatus

Growing community of inventors

Tsuchiura, Japan

Kazuhisa Ishida