Abstract: A large electric dragline having a housing (35) and boom (37) is provided with spaced apart in-line sheaves (34) and (36) at boom point to separate hoist ropes (31) and (32) which are led to the front and rear of bucket (30) respectively. Differential hoist rope control allows accurate and continuous adjustment of the bucket carry angle during all modes of operation. Also described is a computer control system giving continuous accurate control of carry angle by differential hoist rope operation, with manual selection of mode operation.

Abstract: A large electric dragline having a housing (35) and boom (37) is provided with spaced apart in-line sheaves (34) and (36) at boom point to separate hoist ropes (31) and (32) which are led to the front and rear of bucket (30) respectively. Differential hoist rope control allows accurate and continuous adjustment of the bucket carry angle during all modes of operation. Also described is a computer control system giving continuous accurate control of carry angle by differential hoist rope operation, with manual selection of mode of operation.

Abstract: A method of controlling the dump position of a dragline (1) of the type where inclination of the bucket (4) is controlled by differential control of the front hoist rope (7) and the rear hoist rope (8), in order to control dumping too close to the dragline house (2) in a position where the bucket will not release all the load and where slackness in the front hoist rope can cause fouling and serious damage. The complex locus of rear hitch positions (14) that will result in an acceptable dump angle at the bucket when dumped, is empirically transposed to a locus of rear hitch positions (15) at a typical carry angle before dumping, which is in turn approximated by a vertical cylindrical envelope (16). Calculation of when the rear hitch position (13) reaches the envelope (16) may be easily performed by a computer in real time using available parameters such as rear rope inclination and payout values.

Abstract: A method of controlling the dump position of a dragline (1) of the type where inclination of the bucket (4) is controlled by differential control of the front hoist rope (7) and the rear hoist rope (8), in order to control dumping too close to the dragline house (2) in a position where the bucket will not release all the load and where slackness in the front hoist rope can cause fouling and serious damage. The complex locus of rear hitch positions (14) that will result in an acceptable dump angle at the bucket when dumped, is empirically transposed to a locus of rear hitch positions (15) at a typical carry angle before dumping, which is in turn approximated by a vertical cylindrical envelope (16). Calculation of when the rear hitch position (13) reaches the envelope (16) may be easily performed by a computer in real time using available parameters such as rear rope inclination and payout values.