A zinc-nickel alloy plating solution in an aqueous solution comprising, as represented in terms of ions, 4-30 g/liter of zinc and 0.05-4 g/liter of nickel, together with 50-220 g/liter of an alkali hydroxide, 4-110 g/liter of a complexing agent, 0.1-10 g/liter of a primary brightener, 0.01-0.2 g/liter of a booster brightener and preferably, further, 0.01-0.05 g/liter of a tertiary brightener. The ...

There is a parallel roller type roller bearing for an infinite rectilinear motion in which cylindrical rollers move in an infinite circulating passage. Two side plates are attached to both ends of the bearing unit, and a direction change passage communicated with the truck groove and formed in the same horizontal plane is formed in the side plate. A twisting passage is formed between the direction...